Changes to address failures in max_vm_flows and rsyslog.

This is a combination of 2 commits. Commit IDs:
3082041
a90cb6a

The first commit's message is:

1. Using node specific username and password instead of username/
password from inputs.

2. Replacing wait_till_vm_is_up() from nova_fixture with same
routine from vm_fixture.

Change-Id: I79e7f07185100167da712a11da0fc73e94c19d28

The 2nd commit's message is:

Fixing syntax error.
Unmatched [] were causing errors in test discovery,
resulting in review - jenkins job failure.

Change-Id: I79e7f07185100167da712a11da0fc73e94c19d28
Merge "Changes to address failures in max_vm_flows and rsyslog."