Contrib r 3.1.1 intel 2014b

And dependencies (upgraded to latest version) with intel2014b.
Easyblock updates are necessary for generic/rpackage.py and r/rmpi.py 
https://github.com/hpcugent/easybuild-easyblocks/pull/435
This R package has an external dependency on the `GSL` library, so it should be installed using a separate easyconfig file.