Added the arduino-mk-vars.md file to the Fedora SPECfile.

Added some notes to the SPECfile regarding overriding the paths
to the avr tools - most are in /usr/bin, but gcc/g++ are in an
architecture-dependant ccache directory

Upped version to 1.3.2 devel
Merge pull request #162 from sej7278/master

Add arduino-mk-vars.md to the RPM SPECfile.