Added network ifaces collision checking to HA floating IPs
Checking interface and DHCP fixed IP collision

 * Improved the previous implementation of network checking
Fixed previous commit
Added a getter method to get the existing floatingIPs
Added DHCP ranges collision checking
Added a method to check if a given IP is already a floating IP
Check HA floating IP collision when creating DHCP range
Check HA floating IP collision when adding a new DHCP fixed address
Use appropiate hash element to get the IP address
Removed relic-venerable unused code
Completed sub comment with new HA constraint
Check HA floating IP collision when adding a new virtual interface
Check HA floating IP collision when adding a new static interface

 * Also a small refactor from previous commit
Updated changelogs
Unit tests for the FloatingIP model
Using model's global instance
Fixing DHCP range collision unit tests

Comments include reasoning on the changes
Missing lib to use DHCP module
Merge branch 'master' into mjulian/ha-ip-collision

Conflicts:
	extra/scripts/zentyal-unit-tests
Fixed I18N