* provider/consul: first stab at adding prepared query support
* provider/consul: flatten pq resource
* provider/consul: implement updates for PQ's
* provider/consul: implement PQ delete
* provider/consul: add acceptance tests for prepared queries
* provider/consul: add template support to PQ's
* provider/consul: use substructures to express optional related components for PQs
* website: first pass at consul prepared query docs
* provider/consul: PQ's support datacenter option and store_token option
* provider/consul: remove store_token on PQ's for now
* provider/consul: allow specifying a separate stored_token
* website: update consul PQ docs
* website: add link to consul_prepared_query resource
* vendor: update github.com/hashicorp/consul/api
* provider/consul: handle 404's when reading prepared queries
* provider/consul: prepared query failover dcs is a list
* website: update consul PQ example usage
* website: re-order arguments for consul prepared queries
James Turnbull