NS_Tests: add test case TC_sns_bss_add_change_del

1. do SNS configuration
2. add a bind
3. receive the SNS_ADD
4. before answering the SNS_ADD, change the weight via vty and remove the bind

Related: OS#5036
Change-Id: Ibc565bba4c7e0a0b4dd28a48847dbdb998c8528d
1 file changed