Add api tests for load balancer's VIPs and health monitors

Add the following tests:

    1. Create a VIP from an admin user for a tenant other than its own
    2. Update a VIP's description and confirm with a show
    3. Create a VIP specifying address and confirm with list or show
    4. Update a VIP session persistence and confirm with show
    5. Update a VIP connection_limit to other value different than -1 and confirm with show
    6. Update the admin_state_up of a VIP to false and confirm with show
    7. Create a health monitor from an admin user for a tenant id other than its own
    8. Create a health monitor with type HTTP
    9. Update http_method (to POST), url_path (to something other than /) and expected_codes

Change-Id: I2ae2e970cf59ddd10b46e8ae5e4b11d7b5aa6726
Merge "Add api tests for load balancer's VIPs and health monitors"