Converts tabs to spaces

Converts each indentation tab to 2 spaces to conform to best practices.
Updates JSHint gem in use

Updates the JSHint gem to jshintrb from jshint. I have not been able to
find a satisfactory gem for jshint, but this configuration is the one
I’ve found that doesn’t throw errors originating from the gem itself.
Lints JS through JSHint

Corrects formatting issues in JavaScript as exposed by JSHint.