update deps
Updating to support new this.filesSrc property per gruntjs/grunt#606.
Updating to support grunt 0.4.0rc5 and publishing to npm.
Bumping version to 0.1.1rc6 and publishing to npm.

* Updating grunt/gruntplugin dependencies to rc6.
* Changing in-development grunt/gruntplugin dependency versions from tilde version ranges to specific versions.
pulled gruntjs master