Merge pull request #3 from snoyberg/master

GHC 7.6 support
Bump version, and add explicit git repo link to cabal file.
bump pwstore-purehaskell to GHC 7.6
Merge pull request #4 from cdupont/master

bump pwstore-purehaskell to GHC 7.6
compatibility with GHC 7.4
Merge pull request #5 from cdupont/master

compatibility with GHC 7.4
Refactoring and partial implementation of the algorithm
ST Monad is awesome.
Small improvement: hmac256 is now correct.
Fixing the silly error of using .|. instead of xor
Fixed a bug in the algorithm.
One step closer, fixed a bug in computing U_1
Another bug fix in the wall
Fixed another tiny bug.
First working version. pbkdf2 is RFC compliant, perhaps a bit slower
Haddock documentation
Fixed the API to be fully backward compatible
API is fully compatible
Strip trailing whitespace.
Add a note to the docs mentioning the purpose of the new, lower-level API.