AUTO-816: Disconnecting from cass on shutdown

LoggingCQLClient.disconnect is implemented in silverberg 0.1.6. Hence
the version upgrage
kazoo client is stopped on shutdown
lint fix
service super methods called - thanks @glyph
Delete resurrected groups one at a time in batch
Just use delete_group instead, since that gets rid of other related stuff in other tables
Nope, delete_group checks for existance first.  Just use similar logic
Add a desired capacity column 'desired' to the scaling group table
Add a desired capacity value to the group state object
Set the desired capacity on the state object when calculating the delta
trying disconn after supervisor jobs are completed
Merge branch 'master' into auto-816-cass-disconn

Conflicts:
	otter/tap/api.py

Combined health checker info
removing duplicate multiservice creation
Use dict comprehension instead (thanks @manishtomar)
Merge pull request #539 from rackerlabs/auto-874-fix-delete-resurrected-cql

Auto 874 fix delete resurrected cql
Merge pull request #542 from rackerlabs/auto-877-set-desired-capacity-in-state

Auto 877 set desired capacity in state
Merge branch 'auto-816-cass-disconn' into cass-disconn-try

Conflicts:
	otter/tap/api.py
no need for nofify_on_jobs_completion

Can use stopService instead
cassandra_disconnect implemented

that disconnects after supervisor completes stopping
updated tests for cassandra_disconnect