Use sha1 instead sha256 for our updateinfo.xml checksum on el5 (#1080373)

Yum on Python2.4 supports the sha256 checksum type only if python-hashlib is
available, but there is not a hard requirement on it.
Merge pull request #43 from fedora-infra/feature/sha1-on-el5

Use sha1 instead sha256 for our updateinfo.xml checksum on el5
Merge branch 'release/0.9.9.1' into develop
Add update_request to bodhi.update.comment fedmsg payload
Merge pull request #48 from jamielinux/comment-request

Add update_request to bodhi.update.comment fedmsg payload
Add a Release.branchname property
Write a new bodhi.util.get_pkg_pushers to use the new pkgdb2client
Port bodhi.util.get_critpath_pkgs to the new pkgdb2 API
Remove the deprecated pkgdb1 get_pkg_pushers
Merge pull request #50 from fedora-infra/feature/pkgdb2

Port to the pkgdb2
Bump version to 0.9.9.2
Merge branch 'release/0.9.9.2'