Add gcovr python script for coverting gcc coverage output to XML
compatible with Jenkins Cobertura test coverage plugin.

This script is from Sandia:
https://software.sandia.gov/trac/fast/wiki/gcovr

It does reside in subversion and could be mirrored in git and placed as
a submodule. This is a direct copy though.
Script and xsl for taking ctest dashboard output and transforming it
into JUnit compatible XML.

These files were downloaded from the following blog post:
http://www.warp1337.com/content/how-use-ctest-jenkins-xunit-or-junit-plugin