Pin SQLAlchemy to 0.7.x

0.7.10 has been released and is compatible with 0.7.x. Instead
of pinning to 0.7.9, simply pin to 0.7.x to avoid SQLAlchemy 0.8

Also sync the 0.7.x requirements to 0.7.8 (to be in sync with other
OpenStack core components)

Fixes: Bug #1153983

Change-Id: I6f47e7d27fcf0c7271bb2c91a4615ef0bb5e2643
Return 413 when image_size_cap exceeded

HTTP Error 413 (Request entity too large) may be the most appropriate
response when a request to upload an image whose size exceeds
image_size_cap is made.

Addresses bug 1158711.

Change-Id: I4abcb3a8b57c080b5a1b512f9694b2d75a4e5e9d
Add image_size_cap documentation

Add documentation for the 'image_size_cap' parameter.

Addresses bug 1158723.

Change-Id: If6d28a3837dc875b7c8e3e18dd5058eb07b40638
Fallback to inferring image_members unique constraint name

Fixes bug 1160114

The initial version of the 022_image_member_index migration
hardcoded the default naming convention for unqiue constraints
used by PostgreSQL 9.2, which turns out to different to the
convention used by PostgreSQL 8.4. This causes the CI to fail
(non-voting) against RHEL.

We resolve the issue by falling back to inferring the existing
unique constraint name from the image_members indices.

Change-Id: Iad6db033e63cdfd7a77db44bdeaed2284699b469
Merge "Fallback to inferring image_members unique constraint name"
Merge "Add image_size_cap documentation"
Merge "Return 413 when image_size_cap exceeded"
Merge "Pin SQLAlchemy to 0.7.x"