Made it possible to pass a hashed password into Auth::getMobileSession

By default the behavior of Auth::getMobileSession will be the same as
before, but if you set the 3rd argument to false it will not MD5
$password in the request. This way it is possible to md5 this yourself
if you have a reason to do this (I have one, that's why I added this).
;)
Merge pull request #8 from itavero/master

Accept a hashed password on Auth::getMobileSession