Upgrades, add keystone authentification for ostf checker

In case if there is problem with conectivity between
ostf and keystone container, ostf checker won't catch
and user can get broken ostf.

* created separate module clients
* extracted keystone client in separate class
* added ostf client which uses keystone authentification

Closes-bug: #1363054
Change-Id: If5bd2fb6a5736bd043171489ef9615f376a9ed75
Merge "Upgrades, add keystone authentification for ostf checker"