Update gemspec to use only files in git. Fixes #40
Update README: license and contributing.
Merge branch 'master' of github.com:mattconnolly/mongoid-grid_fs into mattconnolly-master

* 'master' of github.com:mattconnolly/mongoid-grid_fs:
  Update README: license and contributing.
  Update gemspec to use only files in git. Fixes #40

Conflicts:
	mongoid-grid_fs.gemspec