Run containerized mistral-api eventlet

Run containerized mistral-api eventlet

The mistral-api container image we use doesn't have the necessary
packages to run via wsgi and this cause puppet to error with:

  "Notice: /Stage[main]/Mistral::Wsgi::Apache/Openstacklib::Wsgi::Apache[mistral_wsgi]/File[mistral_wsgi]: Dependency File[/var/www/cgi-bin/mistral] has failures: true",

Fallback to eventlet mistral-api for the time being until we get
a usable mistral-api image.

Change-Id: Ic10c579aa3b6d0d6a01f120669be3b5dcc5efcda
Depends-On: I54627f1c5a8867738a55bee42075bb6087830c61
Related-Bug: #1724607
(cherry picked from commit e158acb14c4ed92be1a5b961ff1e8ff99b1a5ae3)