Display a warning message when a user is not on the latest version of a module

See the related push request in the SlipStreamServer repository:  https://github.com/slipstream/SlipStreamServer/pull/153

This pull request fix https://github.com/slipstream/SlipStreamUI/issues/30

This is the result:
![islatestversion](https://cloud.githubusercontent.com/assets/2462866/2641324/32291250-bef8-11e3-99b9-c1b03341e0c2.png)