Fixed error in usermodel.loginUser code.

Use the increment function which is just one DB query instead of the two
it takes to get the column value, then update it based on itself. Also,
you don't need to write code to check for a user over and over again,
just do a call to findUser (which should always return the whole user
model btw)
Merge pull request #1 from graysonc/bugfix

Fixed error in usermodel.loginUser code.