Include more R packages in docker image.

This package should be enough to enable the following example http://nbviewer.ipython.org/github/jmchilton/ipython_notebooks/blob/master/cummerbund_galaxy_1.ipynb.

TODO: Extend with more bioconductor packages http://www.bioconductor.org/help/course-materials/2014/SeattleOct2014/.