Fixed lot of stuff in nagios builder

* The ignored hosts are now in separate file instead of being hardcoded, that makes it easier to maintain, the default template should be included (now is missing in git repo, but filename is ignored.host)
* Implemented some default files that must not be removed from icinga objects like ido2db, if you remove them, icinga will not start
* Don't create config files for empty groups, which makes faulty config

Whole this commit is uggly and messy piece of shit but it's 6:40 pm, I am still sitting here in the office, despite I should have been home already, working on this python nightmare (the code is surely cute, but anything written in python gives me creeps) so I really need to commit it anyway, so that I can go home finally :-)

If you don't like anything in this patch, fix it <3

Change-Id: Ib0a51c39a246855fc8240dddba500a5c751c4fa3