Added precondition check to block IPsec configuration without defining a...

...n external interface first

This fix includes a new really basic suite for IPsec.

	IPSec Test Suite
		InstallNonProfilePackages: OK
		EnableModules: OK
		TestIPSecPreconditionPresent: OK
		ConfigNetworkSetExternal: OK
		TestIPSecAddConnectionButtonPresent: OK
		check-zentyal-log: OK
		check-syslog-apparmor: OK