Need to refactor API integration tests

[Anastasia Kuznetsova]

Now we support two API versions in Mistral and have to run both tests suite.
Initially differences between these versions was not very large and we could use same test scenarios for workbooks, executions and tasks in both versions.
Now in v2 we have more endpoints and there are more differences between v1 and v2 and, as a result, we have to test different scenarios for workbooks, executions, but we have the same test suites for them (in v1 and v2).

So need to:
- separate v1 and v2 api tests for workbooks and executions;
- add more complex scenarios for these endpoints in v2
- optimize methods realization for v2 tests (for example we have 3 methods "get_**_definition" for 3 different mistral items, but all of them make the same REST call but for different endpoints. Endpoint can be passed as a parameter.)

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/134224

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/137625

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/137625
Committed: https://git.openstack.org/cgit/stackforge/mistral/commit/?id=407eeb5551011459eb703ae79acb67288b9fa5bb
Submitter: Jenkins
Branch: master

commit 407eeb5551011459eb703ae79acb67288b9fa5bb
Author: Anastasia Kuznetsova <email address hidden>
Date: Thu Nov 27 15:22:04 2014 +0400

    Refactor API tests for v2

    - Separated v1 and v2 api tests for workbooks and executions;
    - Added more tests scenarios;
    - Optimize methods realization for v2 tests.

    Change-Id: Ic24383bc7e6c059088e98eeeeab28ae7bda2de6a
    Closes-Bug: #1384564