Update to ace v1.1.2 / build tweaks

Ace v1.1.2 is missing a tag, but was pushed to the ace-builds repository on 01.08.2014 - ajaxorg/ace-builds@b2f8bf1e745250596afea5b39c70b94421af906d

As well as the update to ace itself, I've added shelljs to devDependencies and fixed a shell command in update.js which was missing a balancing parens and subsequently hung.

The test page editors all seem to work and it works ok on my site, though I can't claim to have tested extensively.

I've left the package version as is as I wasn't sure what your policy for version numbers is (should this be 0.3.0 or 0.2.1?)