Inputmask

Use http://robinherbots.github.io/jquery.inputmask/ for date and time inputs to accept only valid input into datetime fields.

Also fixes a severe typo in the first commit.

That's what it looks like:
![image](https://cloud.githubusercontent.com/assets/133575/4086871/606ff728-2f41-11e4-94d9-bf8fbb8a28ec.png)