orchestration API refactor test_list_resources

Rework test_list_resources so we do a more explicit test of the
resource list which is returned - we expect exactly one resource,
so using assertIn is less explicit than assertEqual.  Refactoring
the code which reads and validates the resource list will enable
other tests to more easily reuse the resource-listing code.

Change-Id: I0c1cb52d92f609781ee21dd3f7d52ceef85e0766
 Improve test_load_balancer_basic

This patch introduces multiple improvements of test_load_balancer_basic.

 1. Use inetd instead of nc on backends.
    Running nc in a while True cycle proved to be ineffective
    and unreliable in case of a relatively big number of
    requests.
 2. Add doc string to NeutronRetriever.
 3. Add setUp method and cleanups for resources
    as a preparation for adding more tests.
 4. Other minor fixes of storing internal values.

Change-Id: I8b5426c9cc832cb8bb5024952535f312cd627d1e
Move the test_utils module to scenario test dir

The test_utils module in tempest.common.utils is only useful for
scenario tests. So it's a little confusing to have it in the common
directory. This commit corrects this by moving the file into the
scenario directory. The service tag requirement for scenario tests
hacking check is updated to only check scenario test files, because
a method in the new utils module was being picked up incorrectly.

Change-Id: I1d70745a5ee07923e680328e5b8a29bfb82d8099
Add load_test mechanism for InputScenarioUtils

Similar to what was done for the negative test framework this commit
adds a method to handle using CONF values with testscenarios.
Previously the attr's were set in the test class definition which
would force a getattr at import time. This will cause issues if the
config file is not present. By adding a method which won't be executed
at import but rather when the tests are run we can avoid this.

Change-Id: Ib635f8b895f6642f78a3af644170700f72259d46
Fix import group ordering in test_utils.py

Per the hacking guidelines the ordering for imports should be stdlib
first, followed by 3rd party imports, and last should the project
imports. However, test_utils.py did not adhere to this ordering. This
commit fixes the oversight.

Change-Id: I0fcc9d137706e841c2e22bd2af8ecd77135c78d2
Up the default timeout for stack builds

This commit ups the default stack build timeout from 600 to 1200.
The stack frequently can take longer than 600 secs to build so
doubling it should give us a safe margin.

Related-Bug: #1297560

Change-Id: I3b13a225793d42e2fa9f4871b2fe81c745954c56
Merge "Move the test_utils module to scenario test dir"
Merge "Add load_test mechanism for InputScenarioUtils"
Merge "Fix import group ordering in test_utils.py"
Merge "orchestration API refactor test_list_resources"
Merge "Up the default timeout for stack builds"
Merge " Improve test_load_balancer_basic"