Remove groupingHash

Based on a chat with @nathansobo and @snmaynard, we're going to try ungrouping
these for more and better context.
Remove respath from exception on all platforms

Before we had the Mac builds reporting paths like app/foo/bar.js and Linux
reporting /opt/local/atom/whatever/foo/bar.js. This fixes that. Its use of
atom.config.resourcePath is maybe brittle.
use getLoadSettings() instead of config object
match forward slash from windows path as well
Merge pull request #8 from atom/dh-truncate-resource-path-cross-platformly

Truncate resource path cross platformly and remove groupingHash