Added new tests for vCenter and fixed old

1. vCenter HA
2. vCenter VMDK driver
3. Changed test set on vcenter_one_node_simple
4. In fuel_web_client.py added volumes_vmdk option
5. For function create_server_for_migration added timeout option

updated:
1.quantity of slaves from 1 to 3
2.and slave_01=controller, slave_02=cinder
3.deleted should_fail variable
4.added in settings : tenant , pass and user
5.updated description of vcenter_vmdk test
6.updated verifying of server's connectivity according with
  real res number instead of comparison with empty string
7. added should fail variable with name of test

Implements: blueprint vcenter-hv-full-scale-support
Change-Id: Id70258b405a6176a7e2bc198e3f541a60b2d4aae
Merge "Added new tests for vCenter and fixed old"