Add npm start & npm test scripts 

This should make it easier for folks unfamiliar with Lineman to get
started.

ping: @jasonkarns @davemo
Remove engine constraint from archetype

This was introduced because of a compatibility problem in node-sass,
which is strictly opt-in now. Additionally, 0.12 is coming soon and we
have no reason to lock this down.
0.21.1
Merge remote-tracking branch 'origin/master'