Overcloud initialization

-Showing list of commands that has to be executed for
 successful initialization
-Loading dashboard_url from Overcloud Keystone catalog,
 when overcloud is initialized
-Hiding list of commands when init is done, meaning we can
access the dashboard_url

-minor fix: Blank parameters are not correctly defaulted on
 heat side. So it's better to default them on heat
 defaults on UI side, until we have passwords auto-generation.

Change-Id: Iba6e2b800e80c867d96b68c66174ebc96df5a7e5
Merge "Overcloud initialization"