Support last modified on listing containers

For now, last modified timestamp is supported only on
object listing. (i.e. GET container)

For example:

GET container with json format results in like as:

[{"hash": "d41d8cd98f00b204e9800998ecf8427e", "last_modified":
"2015-06-10T04:58:23.460230", "bytes": 0, "name": "object",
"content_type": "application/octet-stream"}]

However, container listing (i.e. GET account) shows just a dict
consists of ("name", "bytes", "name") for each container.

For example:

GET accounts with json format result in like as:

[{"count": 0, "bytes": 0, "name": "container"}]

This patch is for supporting last_modified key in the container
listing results as well as object listing like as:

[{"count": 0, "bytes": 0, "name": "container", "last_modified":
"2015-06-10T04:58:23.460230"}]

This patch is changing just output for listing. The original
timestamp to show the last modified is already in container table
of account.db as a "put_timestamp" column.

Note that this patch *DOESN'T* change the put_timestamp semantics.
i.e. the last_modified timestamp will be changed only at both PUT
container and POST container.
(PUT object doesn't affect the timestamp)

Note that the tuple format of returning value from
swift.account.backend.AccountBroker.list_containers is now
(name, object_count, bytes_used, put_timestamp, 0)

* put_timestamp is added *

Original discussion was in working session at Vancouver Summit.
Etherpads are around here:

https://etherpad.openstack.org/p/liberty-swift-contributors-meetup
https://etherpad.openstack.org/p/liberty-container-listing-update

DocImpact

Change-Id: Iba0503916f1481a20c59ae9136436f40183e4c5b

2 files changed, 6 insertions, 2 deletions

diff --git a/api-ref/source/samples/account-containers-list-response.json b/api-ref/source/samples/account-containers-list-response.json
index 4ae34aa4c..d9864aa24 100644
--- a/api-ref/source/samples/account-containers-list-response.json
+++ b/api-ref/source/samples/account-containers-list-response.json
@@ -2,11 +2,13 @@
     {
         "count": 0,
         "bytes": 0,
-        "name": "janeausten"
+        "name": "janeausten",
+        "last_modified": "2013-11-19T20:08:13.283452"
     },
     {
         "count": 1,
         "bytes": 14,
-        "name": "marktwain"
+        "name": "marktwain",
+        "last_modified": "2016-04-29T16:23:50.460230"
     }
 ]
diff --git a/api-ref/source/samples/account-containers-list-response.xml b/api-ref/source/samples/account-containers-list-response.xml
index d8f51cfa0..6e194aebc 100644
--- a/api-ref/source/samples/account-containers-list-response.xml
+++ b/api-ref/source/samples/account-containers-list-response.xml
@@ -4,10 +4,12 @@
         <name>janeausten</name>
         <count>0</count>
         <bytes>0</bytes>
+        <last_modified>2013-11-19T20:08:13.283452</last_modified>
     </container>
     <container>
         <name>marktwain</name>
         <count>1</count>
         <bytes>14</bytes>
+        <last_modified>2016-04-29T16:23:50.460230</last_modified>
     </container>
 </account>