Test and evaluate renjin

[nuest]

renjin (http://renjin.org) is a re-implementation of R for the Java Virtual Machine and can be used directly from Java applications. This could be a significant simplification for WPS4R since no remove RServe server is needed and they even promise better performance.

Goal: breakthrough executing test scripts with Renjin

On the way potentially split up the R executor into a separate module from wps4r because Renjin requires additional Maven dependencies.

• Documentation: http://docs.renjin.org/en/latest/introduction.html
• Introduction: http://www.renjin.org/blog/2013-07-21-alex-bertram-presents-renjin-at-the-r-user-conference-video.html

Known issues for applications: not all packages are available (e.g. sp).