* Fixed mistral cli path: it provides via venv
like in other OpenStack projects
* Added credentials config file like in other projects
* Modified .gitignore
Depends-On: I07aabeace56d3cf336f10085179cd4aa8e0102c3
Change-Id: I742e8124fb8a74e1cca4abb8ddf25950b7b2b2c9