Bug 847133 - [email] Simplify gelam build script and allow for minification

Consolidates build logic in to copy-to-gaia.js script. Allows for minification by changing the "optimize" buildOptions value to either 'uglify' or 'uglify2'. Can also use closure compiler if the script is run in rhino.

Doing a test load using 5 samples, using 'uglify' resulted in a "time to see messages" (not the usual "time to load" first display of something) going from roughly 2863ms before, to 2667.8 after, about a 195 ms savings.

However, for now, the value is set to "none" until further confirmation of a desired value is worked out.