Handle IP Failover in cloud DNAT rules

cc @leplatrem @fredericbonifas @jpcw @regilero
oups,typo
oups,typo,again
optimization
icinga stuff
fix
fix svc dep
better test
Major rework of icinga alerts, cc @regilero
WIP on icinga2 rework
Merge pull request #119 from makinacorpus/stable

Stable