Adding Keystone dockerfile

Patchset 2:
 - Updated Keystone to Openstack Queens version.
 - If Keystone fails container dies.

Patchset 3:
 - Removed port 35357 (no longer used).
 - Added safeguards.
 - Removed warnings regarding to bash.

Change-Id: I50cae8b34f717ff63cbbc1837375a0245d8fccc5
Signed-off-by: Eduardo Sousa <esousa@whitestack.com>