Adding getRemainingLoginAttempts() and getRemainingSuspensionTime() to Throttle model

I think these two functions are very useful for a lot of users.

I considered returning the suspension time as a DateTime object so that it could be more nicely formatted (in the case of different hours / minutes / seconds) but decided to stick with Sentry convention and simply return it in minutes.

I have not tested the Kohana functions as I only use Laravel, but I believe the exact same functions should work there so I have committed that as well..