Support different .jshintrc for tests

[WalkerCodeRanger]

I am switching over to brunch a project created for grunt using yeoman. They setup a different .jshintrc for use with their tests than with the app scripts. This allows them to set the jasmine option and define extra globals for the test. I think something like that makes sense. Please add support for having a different .jshintrc for tests, or potentially for multiple configurable groups of js files.

[paulmillr]

👍