Adds clearTemplate() method

[andersaloof]

Sometimes you need to just clear one template, instead of refreshing everything.

[wraithgar]

Looks good, can you add a test for this?

[HenrikJoreteg]

Sorry this has been sitting too long, I'm not actively using this project and have been having trouble keeping up with maintenance, would be happy to add you if you're interested: https://github.com/HenrikJoreteg/ICanHaz.js/issues/81