Allow gets from multiple different pools

Issue gets to >1 cluster sequentially; if the first pool in the pool list
doesn't have the value, try pool 1, then pool 2, etc. Useful for, e.g.,
migrating data from one cluster to another.

Sets and deletes always go to the first cluster currently.
Merge branch 'master' into multi-get

Conflicts:
	Network/Riak/Montage/Backend.hs
Bump montage version for new riak-bump version requirement
Make the max number of requests configurable
Fixes for 7.6.1
Add a read-only mode

This mode only allows ChainGet and ChainGetMany to be executed by remote clients
Flesh out a few of the show statements for ChainCommand to be a little more readable
Add a flag to log all commands processed by montage
Version bump