Fixed docstring
My unit test suite isn't good enough to mean I shouldn't run 'jules build' -_-
Extra test case! Some fixes to make testing possible.

Especially notable: changes to make jules work outside of CWD.
Fixed up argument naming, other random stuff.
Made huge headway into actual, you know, content rendering. :)

I actually brought back the original component plugin nearly verbatim,
which was nice. I don't agree with parts of the design, but it makes
this easier to merge with master if that's a goal. If merging is impossible,
I can always do whatever the heck I want. :)
Testing actual template rendering, works! Woo