Enable check of Heat engine for Vanilla and HDP

* New parameter "SSH_USERNAME" to config.py was added. This parameter allows to specify SSH user "ec2-user" for Heat engine testing.
* Also unnecessary blank lines were deleted;
* Also IDs of object names were abbreviated to 8 characters.
    For example:
        old object name was '<object-name>-695e5ce7-fc97-4234-abf7-f93f4a70120a'.
        new object name is '<object-name>-695e5ce7'.

Change-Id: Idadd173dd41dea6ecd2a87ac686cd8c656d0ba64
Merge "Enable check of Heat engine for Vanilla and HDP"