Set Content-MD5 after calling webob.Response._app_iter__set.

Discussed upstream at https://github.com/Pylons/webob/issues/86

Fixes bug 1083155

Change-Id: I75c634880e7abaacdcd416c27391e9fdc4874049
Verify size in addition to checksum of uploaded image

Fixes bug 1092584

Previously only the supplied checksum was verified against the actual
checksum calculated by the backend store, with the image being killed
on mismatch.

Now we also similarly verify the supplied image size, if provided.

Change-Id: I87fa3ff77715111f1095f3ebe64cd699776ec27e
Fix import order nits

Change-Id: I972c463131ba688ab9352590eb53f5b1822ac943
Merge "Fix import order nits"
Merge "Set Content-MD5 after calling webob.Response._app_iter__set."