feat: connect sharding manager to control drivers

This patch implements the register/deregister/lookup operations for
the sharding manager.

As a result of this patch, the sharding driver now takes the control
driver as a paramater. This gives it the access needed to make
decisions about queue placement (and lookups) based on the entries in
the control plane.

In order to get the sharding manager working correctly, several
methods had to be overridden to properly handle the QueueNotMapped
error. When a QueueNotMapped error is encountered under normal
conditions, it is equivalent to the target resource not being
found. The overrides mimic the default behavior of those controllers'
methods in the case where the queue isn't found.

An inconsistency was found between the base storage driver and the
concrete implementations. message_controller.list did not provide an
include_claimed parameter. This has been corrected.

To avoid DuplicateOptErrors in the mongodb driver in a sharded
context, a filtering algorithm is applied. To make it clear to data
drivers that they need to apply this filtering algorithm, conf.dynamic
is set by the sharding driver.

Unit tests have been added for the weighted select algorithm.

Up next: sharded queue listing support, caching

Change-Id: Ic36cd657ba13fa4c0b624dc5c71bfe99f9a70139
Partitally-implements: blueprint storage-sharding
Merge "feat: connect sharding manager to control drivers"