ISO Tracker Dev Environment Documentation

[Ara Pulido]

Hello all!

Lately there have been some interest in helping with the development of
the ISO tracker and to avoid that the interest fades away, I've done
something that has been in my TODO list for too long: writing a small
doc on how to set up an ISO tracker dev environment.

The document is in the wiki at:

   https://wiki.ubuntu.com/Testing/ISO/DevEnv

I hope these notes will make it easier for potential contributors.

Cheers!
Ara.