Replacing PHPass with password_compat

Per https://github.com/owncloud/core/issues/10050#issuecomment-51333177

also https://github.com/owncloud/3rdparty/pull/110
That is indeed correct the password_hash method has two params the first is the plaintext password the second is the algorithm to hash with. please refer to https://github.com/ircmaxell/password_compat#usage