Implementation of the JSLint tool for ReviewBot. Parses all uploaded files to a review request and outputs descriptive comments on the relevant .js source files on lines where style errors are found. Options for this tool can be configured in the tool's admin panel. This addition to ReviewBot requires that SpiderMonkey be installed (other engines might also be suitable but have not been tested) to enable the running of the jslint.js linting tool.

manual testing:
- tested jslint on the spidermonkey commandline to make sure that the script itself was working as expected locally.
- posted multiple review requests locally, with js files and non js files, and ensured reviews were generated, with appropriate comments.
- tested what error output the jslint.com website provides for a given file and tested ReviewBot on local dev server tool by posting a review with same file and ensuring output is the same with the same options ticked (seeing that file with errors was being commented by ReviewBot).
- tested changing options in the option panel, and made sure they affected the output of the static analysis tool in locally published reviews. Included print statements in py and js scripts to make sure the correct options were being passed into jslint.