Fuel health check should use public API instead of internal

[Ilya Shakhat]

Green status of OSTF test does not guaranty that the service works via public API. With SSL enabled test "Typical stack actions: create, delete, show details, etc." tells it is green, however user fails to do the same actions via public API due to issue https://bugs.launchpad.net/fuel/+bug/1486611. It would be more helpful if OSTF tests run against the same API endpoints as users do.

Steps to reproduce:
1. Deploy MOS with SSL endpoints enabled
2. Run Stack-related Health Check from Fuel UI
3. Try to create stack via public API
The last step fails with InvalidEndpoint: Prohibited endpoint redirect exception.

[Ilya Shakhat (shakhat)]

VERSION:
  feature_groups:
    - mirantis
  production: "docker"
  release: "7.0"
  openstack_version: "2015.1.0-7.0"
  api: "1.0"
  build_number: "189"
  build_id: "2015-08-18_17-24-26"
  nailgun_sha: "d0b727cdd0d8e7ce5e17e6ea1306d835bfdfb5e7"
  python-fuelclient_sha: "6ad5e0eb4dbbca6cade3444554606927ecd3f16f"
  fuel-agent_sha: "57145b1d8804389304cd04322ba0fb3dc9d30327"
  fuel-nailgun-agent_sha: "e01693992d7a0304d926b922b43f3b747c35964c"
  astute_sha: "e24ca066bf6160bc1e419aaa5d486cad1aaa937d"
  fuel-library_sha: "7c80eed2119260cc15a700068b9eb20ccc773926"
  fuel-ostf_sha: "235f21b230fea15724d625b2dc44ade0464527e2"
  fuelmain_sha: "c9dad194e82a60bf33060eae635fff867116a9ce"