Port code to use consul

This patch is intended to preserve the
current functionality of the orchestrate module
using cosul as the backend instead of etcd.

It includes the following changes:

- each client connects to its local
etcd agent
- current_version is written to the consul kv store
- ping just checks if the local consul client is functional
- puppet/validation are tracked as checks (with failures
logged as warnings so they do not cause services to become
unregistered
- running version ported to consul kv entry
update_own_info should delete previous versions

we were relying on a ttl from etcd to ensure that
only the lastest version was ever written into the
kv store.

consul does not support ttls on the kv store, so we
need to ensure that we clean out old versions so that
check_sinlge_version and friends will actually work.

it is worth noting that this implementation is likely
temporary and that version might wind up being some
kind of health check instead. for that reason, the
potentially performance issues are not that big of
a deal.
fix tests

related to the etcd deprecation changes
Add local health capability

so that we can easily know if our
local services are failing
Merge pull request #19 from bodepd/deprecate_etcd

update etcd to consul for k/v