Build: Add a script to generate a Makefile from specfile dependencies

'makemake.py' pulls dependency information out of the RPM spec files (specifically the 'BuildRequires' tag) and generates a Makefile which can then be used to build all the RPMs in dependency order.

This is a first cut!   Known problems include:
 * Make may not be the right tool for this - we may be better off handling the build tasks ourselves rather than generating a makefile.    This might make it easier to spread the work out over a build cluster.
 * The script generates naive rules for rpmbuild jobs which produce multiple targets.   There's a risk that we either rebuild too much or not enough.   See the dire warnings at:  http://www.cmcrossroads.com/article/rules-multiple-outputs-gnu-make 
 * The script needs quite a bit of tidying up.   We don't need to create a dict mapping spec_file_name -> spec; we should be able to generate all the dependency information in one pass;  pylint still complains about variable naming issues.