Updates to use a cache per call type

I've updated all the places in aweplug that do REST calls to use a
cache per type (one for videos, one for quickstarts, etc.) instead of
the single site wide cache. There is now no default ttl in the cache
itself, you'll need to specify one when you create a new instance of
the cache.

Please go over the defaults I have put in place and see if they make
sense.
Merge pull request #75 from LightGuard/cache_enhancement

Updates to use a cache per call type