Changed nodepools to pools

Made lb_method and subnet_id option attributes in old extension, but plugin code raises exception if not specified.  Likewise for lb_algorithm in new extension and plugin.

Change-Id: I416c424b34e8488efd6d68d5dd2cf04c647ae1b1
Merge pull request #8 from brandonlogan/nodepools_to_pools

Changed nodepools to pools
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
Adding healthmonitor db unit test cases