Clean up the CMake code around the python modules and uninstalling
- It isn't possible to build python extensions using distutils that
link to things that we are building, because CMake provides no
means for a custom command to depend on a library. Build them
using CMake directly instead
- Clean up the tests: the tests depended on having a working opengl
and core plugin xml file and were also sensitive to xml data. Make
a mock.xml and use that instead
- Require ini for the compizconfig-python tests. They won't run without it
- Fix the uninstall scripts. We were clobbering the uninstall target
with the python uninstall targets, that is just plain wrong. Created
a new cmake function to append custom uninstall scripts to the global
uninstall script. Approved by Daniel van Vugt.