setup makefile to build firmware stuff

We gave up on converting firmware build stuff to CMake, so were leaving
it with SCons.  The makefile in the root of the project now calls scons
when building firmware targets.  The scons stuff is now all contained
under the firmware folder

note: also removed git_version from firmware
Merge branch 'cmake' of https://github.com/robojackets/robocup-software into cmake