Add script/escape-non-ascii, escape as \u####

There's no reason MathQuill should be required to be loaded as UTF-8
when non-ASCII Unicode characters can easily be escaped, but MathQuill's
source should have beautiful readable Unicode characters.

Combines the best of http://stackoverflow.com/a/15601944/362030 with
http://stackoverflow.com/a/16987522/362030
Merge branch 'build.escape-non-ascii' into dev