Can now build libat90 using cmake

we still need to add the rest of the repo to use cmake and fully
migrate off plain makefiles. This will also help with issue #7 and #1
Added TemplateNode to cmake build system
Added GPSNode to cmake build
Now have all targets building with cmake
We should now be able to write the node binary to the avr using avrdude
Removed old Makefiles
Updated readme with info about the new cmake build
Merge branch 'master' of github.com:UnicornRaceEngineering/g5-nodes