style($templateCache): remove trailing whitespace

This was introduced by 2ca6d650e8a13cee28f11c38622cab231787325f, somewhat inexplicably as I had run
grunt ci-checks locally. But regardless, this should fix this up.
docs($cacheFactory): document cache instance methods

These were apparently entirely undocumented. I'm not sure if they're intended
to be private, but in case they're not, I've written some initial docs for them