add defaults for *_BACKEND
load MD5PasswordHasher during setUpClass, greatly boosts TestSpeed
Use Django PasswordHashers system, port hashers
add Sha512 password hasher
Add PASSWORD_HASHERS, remove HASH_* settings
update changelog
update TODO
add a TODO
document new settings for 0.6.1
document PASSWORD_HASHERS setting
update TODO list
update TODOs again.
merge Middlewares for a minor speed improvement
update todo
add another TODO
add set_password_hash method
implement set_password_hash function
starting to port restauth-import to backends
do more rigorous checks on the input file
minor pep8 cleanup