replace Python bundles pytools, pygraphics and pyanalysis with meta-RPMs

With SPI-1137, as discussed at the LIM some time ago, we will not need anymore the Python bundles, and dependencies on the RPMs of the python packages will be enough.

We will not be ready with the fine grain dependencies for LCG 95, so we will require that the bundles get replaced with meta-RPMs that pull the actual packages.