Switched to JSHint for node diagnostics

This pull request switches from using JSC with the custom python script to Node.js with the JSHint command-line tool.

This allows users to override the JSHint options in the following order:

* /* jshint */ comments
* $CHOC_PROJECT_DIR/.jshintrc
* $HOME/.jshintrc

Users can also configure JSHint to skip some files you can list them in a file named .jshintignore in the directories above as well.