`isUsingRequireJS` failsafe.
adding rev task
Merge pull request #66 from stephenplusplus/master

`isUsingRequireJS()` won't fail if main.js doesn't exist.
Merge pull request #72 from revathskumar/rev

adding rev task
prepare for new prompt()s
Merge pull request #73 from stephenplusplus/new-prompt

prepare for new prompt()s