Upgrade report for 1.7 to 2.x

I am happy to report that with a few fixes, I was able to upgrade my home installation from 1.7 to the current 2.x Debian packages.

It's actually pretty painful - i had to:

1. package Drush 5
2. fixup the Aegir Debian packages installed files
3. run the hostmaster upgrade twice, as it failed because of the drush commandfile cache (fixed in hostmaster-migrate by running drush @hostmaster cache-clear drush after the upgrade, see #1612044)
4. run drush @hostmaster hosting-setup to reinstall the crontab, probably because of the failure in the last step
5. remove the provisionacl module which needs to be ported.
6. disable the hosting-queue runner (it also needs to be ported, see #1189556)

But still, the future is looking much brighter now - i feel we can start considering Aegir 2.x as a real development environment now that upgrades work correctly. :)

Note that this is NOT READY FOR PRODUCTION. Do NOT upgrade your current production installs to 2.x, as very few people are actually running this code right now.