Log a message when image object not found in swift

We should log when a request for an image object in swift returns a 404.

Fix for bug 1227786.

Change-Id: I27a970840cf448196245ba1e58523b9e0b1495f5
Cleanup and make HACKING.rst DRYer

Reference the OpenStack hacking guide in HACKING.rst and remove
duplicate entries. Adds placeholder section for glance specific
rules.

Change-Id: I1bfff8c69c9370e2d648197b7e71e229695ef627
Add config option to limit image properties

This patch adds the image_property_quota config option. This allows a deployer
to limit the number of image properties allowed on an image. The default value
is 128, as is currently the limit enforced by nova. Users will only be able to
update an image if the result of the transaction would be under this limit.
This behavior is intended to be similar to 'quota_metadata_items' in nova.

This is for both Glance v1 and v2.

Fixes bug 1251518
docImpact

Change-Id: I4aa9504deae836404f11c9ada71a91f85caeba4c
Merge "Add config option to limit image properties"
Merge "Cleanup and make HACKING.rst DRYer"
Merge "Log a message when image object not found in swift"