Remove an unused mine.get
fix the service template
Register a service for postgresql
Use Consul service discovery to handle Replication discovery
Restrict to a subnet, not to specific IP addresses

Originally this was designed so that a leaked password is only
useful on the system it was designed for. However doing this relies
on mine.get in order for it to actually provide any sort of security
and mine.get takes a long time to update.

This will still prevent people from *other* networks being able
to access the databases and we can investigate using TLS client
certificates instead of passwords as well.
Stop using postgresql-consul on the server
Switch monitoring to use consul to discover postgresql
Wait 10s instead of 1s
Document the new way to do service discovery
Merge pull request #18 from dstufft/postgres-consul

Switch to using Consul to discover the PostgreSQL instances.