Add swift_store_ssl_compression param

Add a new glance-api.conf parameter 'swift_store_ssl_compression',
which allows disabling SSL layer compression for https swift requests.

This can increase performance when transferring compressed images (eg
qcow2) to/from swift.

Addresses bug 1190666.

DocImpact.

Change-Id: Ic26dba9dce5ea7e5c09fdd531746b93cec54fc5c
Cache cleaner wrongly deletes cache for non invalid images

Based on current implement of method delete_stalled_files,
it's just deleting all the images located in /incomplete
instead of using the param 'older_than' to check if it
should be deleted. So this fix will use 'older_than' to
confirm brfore deleting.

Fixes bug 1228256

Change-Id: Ica27915f8b9b098ecae1e38c8e678d6acf4f2f76
Change response code for successful delete image member to 204.

The delete image member call currently returns 200 with no response
body.  According to the API contract, 200 means to expect a body.
This patch changes the response code to 204.

Change-Id: Id48187b3c47e39075a352d3027dd3d3451d46905
Closes-Bug: #1229366
Merge "Cache cleaner wrongly deletes cache for non invalid images"
Merge "Change response code for successful delete image member to 204."
Merge "Add swift_store_ssl_compression param"