throw an error when incorrect args are passed to `.helpers()`
loader-cache and updating test/layout.js

Adding loader-cache and some additional methods for default loading template types.
Updated test/layout.js so far to see if this is the way we want to go
loaders
new loader-cache changes
use splice
fix pluralization
simplify loader logic
reset params
Merge remote-tracking branch 'origin/loader-cache' into loader-cache-3

Conflicts:
	index.js
splice in default loader
_load
cleanup, run verb
rename `defaultLoaders` to `mixinLoaders`
moving some code to normalize
handling loader stacks when loading template types
async loaders first pass
async, promise, and stream loaders
removing dep
minor formatting, remove `_.cloneDeep` from bindHelpes
Merge remote-tracking branch 'origin/loader-cache' into loader-cache