Add API Sample tests for Snapshots extension.

Partially implements blueprint nova-api-samples
Modifies fakes to produce a real timestamp
Fixes bug 1126211

Change-Id: I8973d50fa67abbf6f96684ff8a0b898912f09caf
Merge "Add API Sample tests for Snapshots extension."
Merge remote-tracking branch 'm_src_repo/master' into build-temp