Added package directory with RPM SPECfile (and instructions!)

Linked to issue #144

Tested on Fedora 18, works fine except the ard-reset-arduino manpage displays
[1m and [0m around some headings, might be a bug in help2man 1.41.2 as it
works fine on Debian with 1.43.3, will try CentOS/OEL 6.5 next.

I didn't update the changelog as I didn't know what the new development
version is going to be.