Resolve compiler path using requre algorithm

I was having a issue with accord resolving the path for one of the compilers in a roots project. [roots-cms](github.com/carrot/roots-cms) has [roots-cms-client](github.com/carrot/roots-cms-client) as a dependency, and they both share coffeescript as a dependency. Because of how [npm installs dependencies](https://github.com/npm/npm/issues/1341), coffeescript doesn't get installed into `roots-cms/node_modules/roots-cms-client/node_modules`, instead node will see that `roots-cms` shares that dependency and only install it into `roots-cms/node_modules`.

This updates accord's `load` function to resolve the compiler path the same way `require` does using [node-resolve](https://github.com/substack/node-resolve).