ZOOKEEPER-3436: Enhance Mavenized Make C client

Based on eolivelli 's [previous pull request](https://github.com/apache/zookeeper/pull/993) we enhanced now the maven C client build:

- we can compile now the C-client without tests (using the -DskipTests option)
- we can optionally enable the test coverage calculation for the C-client (-Pc-test-coverage)
- we also package the C-client into the binary tarball (when -Pfull-build is used)
- I also updated the README_packaging.md file to make user's life easier (happier? :) )

I tested the build on ubuntu 16.04.

Author: Mate Szalay-Beko <mszalay@cloudera.com>
Author: Enrico Olivelli <eolivelli@apache.org>

Reviewers: nkalmar@apache.org, eolivelli@apache.org, andor@apache.org

Closes #1078 from symat/ZOOKEEPER-3436 and squashes the following commits:

18250df41 [Mate Szalay-Beko] ZOOKEEPER-3436 remove the C binaries from the binary tarball; update the readme files
57b7cd61d [Mate Szalay-Beko] ZOOKEEPER-3436 fixing file permissions of usr/bin/* in binary tarball
a2ac025a0 [Mate Szalay-Beko] ZOOKEEPER-3436 enhance / format README_packaging.md
30eea5e27 [Mate Szalay-Beko] ZOOKEEPER-3436 exclude README_packaging.md from license check
936550e48 [Mate Szalay-Beko] ZOOKEEPER-3436 fixing README_packaging.md
f01029524 [Mate Szalay-Beko] ZOOKEEPER-3436 Enhance Mavenized Make C client
44f6ba5d2 [Enrico Olivelli] Better .gitignore
204603751 [Enrico Olivelli] Enhance Mavenized Make C client

1 files changed, 89 insertions, 0 deletions

diff --git a/README_packaging.md b/README_packaging.md
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index 000000000..fe731a7ff
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+# README file for Packaging Notes
+
+The ZooKeeper project publishes releases as tarballs.  For ZooKeeper packages
+specific to your OS (such as rpm and deb), consider using Apache Bigtop:
+
+http://bigtop.apache.org/
+
+
+## Requirements
+
+- ant (recommended version 1.9.4 or later for concurrent JUnit test execution) or maven to build the java code
+- gcc, cppunit and python-setuptools are required to build C and python bindings.
+
+On RHEL machine:
+
+```
+yum install cppunit
+yum install python-setuptools
+```
+
+On Ubuntu:
+
+```
+apt-get install cppunit
+apt-get install python-setuptools
+```
+
+
+## Package build command (using maven)
+
+Commands to clean everything and build the tarball package without executing the tests: `mvn clean install -DskipTests`
+
+
+`zookeeper-assembly/target/apache-zookeeper-<version>-bin.tar.gz` tarball file structure layout:
+
+- `/bin`    - User executables
+- `/conf`   - Configuration files
+- `/lib`    - ZooKeeper JAR files and all the required java library dependencies
+- `/docs`   - Documents
+  
+Beside the binary tarball, you can find the whole original source project packaged into: 
+`zookeeper-assembly/target/apache-zookeeper-<version>.tar.gz`
+
+
+### Building the C client (using maven)
+
+To also build the C client, you need to activate the `full-build` profile:
+ 
+```
+mvn clean -Pfull-build
+mvn install -Pfull-build -DskipTests
+```
+
+Optional parameters you might consider when using maven:
+-  `-Pfull-build`         -   activates the full-build profile, causing the C client to be built
+-  `-DskipTests`          -   this parameter will skip both java and C++ unit test execution during the build
+-  `-Pc-test-coverage`    -   activates the test coverage calculation during the execution of C client tests
+
+Please note: if you don't provide the `-Pfull-build` parameter, then the C client will not be built, the C client tests
+will not be executed and the previous C client builds will no be cleaned up (e.g. with simply using `mvn clean`).
+
+The compiled C client can be found here: 
+- `zookeeper-client/zookeeper-client-c/target/c/bin`                 - User executable
+- `zookeeper-client/zookeeper-client-c/target/c/lib`                 - Native libraries
+- `zookeeper-client/zookeeper-client-c/target/c/include/zookeeper`   - Native library headers
+
+
+## Package build command (using ant)
+
+**Command to build tarball package:** `ant tar`
+
+`zookeeper-<version>.tar.gz` tarball file structure layout:
+
+- `/bin`              - User executable
+- `/sbin`             - System executable
+- `/libexec`          - Configuration boot trap script
+- `/lib`              - Library dependencies
+- `/docs`             - Documents
+- `/share/zookeeper`  - Project files
+
+
+**Command to build tarball package with native components:** `ant package-native tar`
+
+`zookeeper-<version>-lib.tar.gz` tarball file structure layout:
+
+- `/bin`                 - User executable
+- `/lib`                 - Native libraries
+- `/include/zookeeper`   - Native library headers
+