Improve a bit performance of Ceilometer

we shouldn't use <array>.extend([<generator>]) it's similiar to
<array>.extend(<generator>) but slower

Change-Id: Ic859e9a477f03b680e1ac0db1498261a3dc24997
Add keystone control exchange

This patch adds
1) Notification exchange for keystone
2) Abbility to profile keystone

In future we are going to add as well keystone
audit notification pluging

Change-Id: I21f78698431ef9da9ddf5771a0594e5ab7f755a5
Merge "Add keystone control exchange"
Merge "Improve a bit performance of Ceilometer"