Implemented expanded file selector, options, added unit tests

I needed this functionality but found the previous version didn't support the standard grunt expanded file selector functionality (`cwd`, `rename` etc).

So I went ahead and rewrote the task on a base of `grunt-contrib-copy`, with some added options based on @cha0s's fork.

To make it official I added unittests using `grunt-nodeunit`, they run with the default `grunt` command.

To put cherry on top I also bumped to 0.3.0, made myself contributor (hah! :) and  added the new options to the readme.