This patch adds ArcanistJSHintLinter class and three new .arcconfig options:
* lint.jshint.prefix - directory where JSHint binary resides
* lint.jshint.bin - JSHint binary name (if different from 'jshint')
* lint.jshint.config - a JSON file with JSHint project-wide options
By default, this linter assumes that JSHint is installed on user's system
as an NPM package.
Test Plan:
(1)
Run `npm install jshint -g` to install JSHint and add
ArcanistJSHintLinter to your Lint Engine (I didn't see PEP8 or
PyFlakes in the PhutilLintEngine so I decided to not to put
JSHint in there). After that you can do `arc lint my.js`.
(2)
Create a new file, config.json, and add `{ "white": true }` in it.
Add `"lint.jshint.config": "/path/to/config.json"` to your .arcconfig and
run `arc lint my.js`. After that, unless your name is Douglas Crockford,
you'll see tons of JSHint warnings about minor PEP8-like things (spacing, etc.)
