defaults:

 - change the order of defaults (although not being used right now)
 - add `.md` to extensions of default engine
adds `assets.md` to docs
clean up deps
start updating docs
clean up stack.js
linting, formatting
use gulp-extname for ext plugin
use rewrite-ext in path plugin
update test to reflect `md`

`md` was added as an extension for the default engine
update deps
Merge remote-tracking branch 'origin/v0.6.0' into v0.6.0

Conflicts:
	lib/plugins/init.js
	lib/plugins/renderer.js
	lib/stack.js
change `debug` plugin to `inspect` to avoid conflict with glob
rename plugins
update plugin variable names
Merge remote-tracking branch 'origin/v0.6.0' into v0.6.0