Multitenancy

### Support multi company
* New command `openchange_neworganization --firstorg=NAME_OF_THE_ORGANIZATION`
* Add users using `openchange_newuser --create --firstorg=NAME_OF_THE_ORGANIZATION whatever@foo.com`
* User log in with their full email address
* Users only see contacts from their organization

### Dependencies runtime

Without this the multitenancy support won't work, but the normal behaviour will.

* Change on sogo openchange to encode usernames properly: https://github.com/Zentyal/sogo/pull/27
* Change on samba adding an option: https://github.com/Zentyal/samba/pull/4

### Usage requirements
* It will require to do migration of data.
 * `openchange_provision --migrate` (it's idempotent)
 * New versions of openchange must include this command in post install script
* New usage: add `--firstorg` attribute to every openchange_* command