1165355 - Sanitize checksum types.

SHA and SHA-1 are the same checksum algorithm, but Pulp considered them
to be separate algorithms. This commit ensures that Pulp no longer
stores the SHA-1 algorithm as "sha" in the database, and it also
contains a migration that resolves existing "sha" objects.

https://bugzilla.redhat.com/show_bug.cgi?id=1165355
Merge branch '2.4-dev' into 2.5-testing

Conflicts:
	plugins/pulp_rpm/plugins/importers/yum/parse/treeinfo.py
	plugins/pulp_rpm/plugins/importers/yum/upload.py
	plugins/test/unit/plugins/importers/yum/parse/test_treeinfo.py
	plugins/test/unit/plugins/importers/yum/repomd/test_metadata.py
	plugins/test/unit/plugins/importers/yum/repomd/test_primary.py
Merge branch '2.5-testing' into 2.6-dev