Added:plugin unit tests:DB listener description

Change-Id: I03e70db6fe0a05cb34d74bdca33df83ce23d82d9
Merge pull request #7 from the2hill/unit-tests

Plugin unit tests for api and obj model improvement
Added create load balancer db test.

Change-Id: I91199f707670fea316168dc35d6ed63490b1e2bf
Created listener, nodepool, member, and health monitor contexts, create methods, and simple create tests.

Change-Id: I29c15699296a45cc09f467949dd24c55562553e0