Throw better exception is a rule object is missing corresponding Trigger object.
Update gitpython dependency to newest version to avoid AttributeError exception.
Merge pull request #911 from StackStorm/STORM-883/mistral-integration-tests

Move unit tests to separate directory
Merge pull request #918 from StackStorm/update_git_dependency

Update gitpython dependency to the newest version to avoid AttributeError exception
Merge pull request #917 from StackStorm/throw_on_missing_trigger_object

Throw better exception if a rule object is missing corresponding Trigger object
Closes #919
Merge pull request #920 from StackStorm/pwh/fabricrunner_fix

Closes #919
Add system integration tests for mistral

Add system integration tests for mistral. The tests assume both st2 and mistral are running on localhost. These tests are not run by default.

```
~/st2$ make itests

==================== integration tests ====================
The tests assume both st2 and mistral are running on localhost.

. virtualenv/bin/activate; nosetests -s -v st2tests/integration || exit 1;
test_basic_workflow (integration.mistral.test_wiring.TestWorkflowExecution) ... ok
test_complex_workflow (integration.mistral.test_wiring.TestWorkflowExecution) ... ok
test_cpu_count (integration.mistral.test_wiring.TestWorkflowExecution) ... ok
test_workflow_failure (integration.mistral.test_wiring.TestWorkflowExecution) ... ok

----------------------------------------------------------------------
Ran 4 tests in 10.176s

OK
```