self-provisionning support

Hosting setup needs to be rerun (and rerunnable) when migration of aegir is be finished so that the cronjob gets fixed.

So that's nice: we can deploy a new site using the backend, but what about the frontend? We have yet to be able to migrate Aegir itself, from the frontend. I think it's a reasonable goal.

So I'll be posting the migration instructions in the UPGRADE.txt file. I found two bugs during testing, in the backup system, which i fixed in those commits:

http://drupal.org/cvs?commit=217648
http://drupal.org/cvs?commit=217654

I also had to verify the d6 platform through the web interface first, because otherwise it would fail like this:

sh-3.1$ /var/hostmaster/drush/drush.php --debug --verbose=2 provision verify
Drush bootstrap phase : _drush_bootstrap_drupal_root() [0.051 sec]   [bootstrap]
Initialized Drupal 6.12 root directory at /var/hostmaster/drupal-6.12   [notice]
[0.094 sec]
Found command: provision verify [0.097 sec]                          [bootstrap]
Initializing drush commandfile: provision_apache [0.097 sec]         [bootstrap]
Initializing drush commandfile: provision_drupal [0.103 sec]         [bootstrap]
Initializing drush commandfile: provision_mysql [0.103 sec]          [bootstrap]
Including                                                            [bootstrap]
/var/hostmaster/.drush/provision/web_server/verify.provision.inc
[0.104 sec]
Including                                                            [bootstrap]
/var/hostmaster/.drush/provision/platform/verify.provision.inc [0.112
sec]
Including                                                            [bootstrap]
/var/hostmaster/.drush/provision/db_server/verify.provision.inc
[0.118 sec]
Could not connect to the master database. [0.155 sec]                [error]
An error occurred at function :                                      [error]
drush_provision_mysql_provision_verify_validate [0.156 sec]
Command dispatch complete [0.156 sec]                                   [notice]

We are likely to need the #500362: dispatcher locking if we want to run concurrent frontend installations (which is probably required to have the frontend upgrade itself.

See also #588114: cannot upgrade aegir with itself because the frontend doesn't follow.

So the current state of affairs is this:

1. we can migrate a hostmaster site using the hostmaster-migrate command, in the backend
2. the UPGRADE.txt recommends the hostmaster-migrate process
3. we cannot yet provision-install hostmaster sites (see #711740: allow install of hostmaster sites in provision-install)
4. the install process can setup only provision or the whole thing, but lacks some glue to run hosting-setup and other things (#711760: separate backend and frontend install process)
5. we cannot yet migrate or clone hostmaster sites from the frontend (see #711746: allow upgrade of hostmaster sites from the frontend)

Once all this is done, we can change the project name to Skynet, a few expert systems, neural networks and new AI thingies, hook it up to some nukes, and watch the fireworks. ;)

Just a note here to mention that #500362: dispatcher locking was implemented, which theorically makes it possible to run the frontend dispatcher on multiple servers at once.