Add jshintrc and make it pass

- Expected '===' and instead saw '=='.
- 'alert' is not defined.
- 'document' is not defined.
- 'jQuery' is not defined.
- 'mw' is not defined.
- 'sajax_do_call' is not defined.
- 'sajax_request_type' is not defined.
- 'index' is defined but never used.

Change-Id: Ie0b5c162c42166828f59a366e0cf51c21efb2c89