Change OpenStack credential terms(Proposed)

Replace API key with Password as OpenStack users use PASSWORD even while defining env variable.

Replace Authorization URL with "Authorization Token URL"

Authorization URL refers to http://xxx.xxx.xx.xx:5000/v2.0/
[We set OS_AUTH_URL with this]
What bosh-bootstrap needs is http://xxx.xxx.xx.xx:5000/v2.0/tokens

I think this should be opened for discussion as per user's perspective.