Feature/bgp ipv6

Tests for configureBGP junos actions using ipv4 and ipv6.
These tests prove configureBGP action is suitable for ipv4 and ipv6.
There are no IPProtocolEndpoints being created nor used in configureBGP workflow in the capability, so BGP capability should be able to work with both types of IP addresses.

This commit also adds the feature in BGPModelFactory for setting session description with value read from properties (in the past it was hardcoded to "description", which is now kept as a default value).