Merge branch 'release/0.9.7.2'
Set the 'updated' field of the updateinfo to the PackageUpdate.date_modified
Refactor our cached updateinfo handling (#960642)
Keep older security updates in the updateinfo (#259)
Set the update.date_modified in the tests
Merge branch 'release/0.9.7.3'
bump version to 0.9.7.4
Merge branch 'release/0.9.7.4'

Conflicts:
	bodhi/metadata.py
	bodhi/tests/test_metadata.py
Merge with the metadata.py from the develop branch
Don't accidently re-open closed bugs