* adding missing options
* unification of help

Change-Id: I2365e66433b63de8fd4da205611d9c1bf3bb6730

Change-Id: Ie0787d5ffbee0a7d2429cb285fa6ecdf722e4ae1

According to help `swift upload -h` you can add a customized request header 'Content-Type'.
But actually it is ignored (cleared and default is used) if subcommand is upload.

Subcommand post works as expected in help.

Bug fix: Use 'Content-Type' from the customized request headers also if
uploading.

Change-Id: If0d1354b6214b909527341078fe1769aa6587457

 * Always use testtools.TestCase, since we're relying on testtools
 * Always use mock (as opposed to unittest.mock) since we're relying on
   mock
 * Add note about when a missing logging handler was added
 * Stop %-formatting the giant usage string that doesn't actually need
   any formatting
 * Prefer assertIs, assertIn, assertIsInstance over assertTrue
 * Use else-self.fail instead of sentinel values
 * Check resp.get('error') is None before checking resp['success'] is
   True, so test failures actually tell you something useful
 * Tighten some isinstance assertions
 * Import MockHttpTest from correct location
 * Only populate clean_os_environ once
 * Use setUp for setup, not __init__
 * Replace assertIn(key, dict) and assertEqual(foo, dict[key]) with
   assertEqual(foo, dict.get(key)) when key is a literal and foo is not
   None
 * Use mock.patch.object instead of manually patching for tests
 * Use six.binary_type instead of type(''.encode('utf-8'))
 * Stop shadowing builtin bytes
 * Reclaim some margin
 * Stop checking the return-type of encode_utf8; we already know it's
   bytes

Change-Id: I2138ea553378ce88810b7353147c8645a8f8c90e

Cleanups for change I35c3b266b3c733f6b1629de4c683ea7d40128032

Add missing param definitions to client get_container
and head_object docstrings.

For consistency, add headers parameter to the Connection class
head_object and head_container wrapper methods.

Add tests to verify that the headers parameter of Connection
get_container, head_container and head_object methods is passed to the
module functions.

Change-Id: Ib40d5b626b2793840727c58cffbf725bea55651f