Checksum may use upper/lowercase letters
bag-info.txt all metadata elements may be repeated
Allow bags with v0.97
add tagmanifest entries to Bag.entries
Check for missing tagfiles in optional tagmanifest(s)
Up version of generated bags
Add test for optional tagfile validation
Update for Py2.5 compatibility
Update version in tests to 0.97
Add test comment
make_bag support for multiple metadata with same header
upped version to v1.1.0 for release to pypi