Accept a full .jshintrc configuration file

[wrobel]

I'd like to be able to provide a complete JSHint configuration file for the JSHint run. There are a few options that require an integer setting (such as 'maxcomplexity', 'maxlen', etc.).

The proposed solution does not heed the 'withDefaults' options. Would it be better to heed that setting with a jshintrc file as well?

I would add the necessary documentation for README as well in case you deem this pull request acceptable.

[jonahkagan]

Are there rules that require a full JSHint config file that aren't covered by Coffeelint? Rules like maxlen and maxcomplexity are probably better served by Coffeelint, since it lints the actual CoffeeScript code you write, not the generated JS. For example, if you have a line that exceeds your max line length in CoffeeScript, it might be compiled into a few shorted JS lines.

I've been meaning to add a note about using Coffeelint in conjuction with coffee-jshint to the README. My hope is that eventually Coffeelint will develop enough functionality to make coffee-jshint obsolete.