rccn/install: Add compatibility shim to use python2 or 3
rccn/install: Add compatibility shim to use python2 or 3

Allow for running the install script with python2 or python3. The main
change involved updating to the new print function syntax and
importing the python2 future functions for backwards compatibility.

Rhizomatica/rccn,Rhizomatica/rccn,Rhizomatica/rccn,Rhizomatica/rccn,Rhizomatica/rccn