Support for .recessrc file

This PR adds support for reading options from a `.recessrc` file, as you would expect from similar plugins such as `gulp-jshint`, etc.

Also happy to do the equivalent for the `grunt-recess` plugin if you're happy with the implementation here.
The idea was to allow for plugin consumers to be able to specify option overrides (either individual config options via an object literal or by specifying a path to the specific rc file they want to load).

Personally I think it's a bit at odds with having an rc file- it seems like it should be one or the other not a mix of both, but I added the option as it was an available parameter of the `rcloader` that I assumed was standard practice.

I've just checked the jshint plugin (gulp and grunt) and noticed that in those cases, if an rc file is specified the settings are *not merged*. So I guess this doesn't need to be here. ;)

I'll remove, rebase and then this should be good to merge. :+1: