If a user attempts to setup a database while not connecting using
the network, port is NULL and thus fails constraint checks. Instead,
we now use the default Postgres port of 5432 when this happens.
Also, setup_db() is renamed to setup_timescaledb() for clarity in
the presence of other extensions.
Setting up single node is now:
```
CREATE EXTENSION IF NOT EXISTS iobeamdb CASCADE;
select setup_single_node();
```
To setup a cluster do (on meta node):
```
CREATE EXTENSION IF NOT EXISTS iobeamdb CASCADE;
select set_meta();
```
on data node:
```
CREATE EXTENSION IF NOT EXISTS iobeamdb CASCADE;
select join_cluster('metadb', 'metahost');
```
This assumes that the commands are issued by the same user on both the
meta node and the data node. Otherwise the data node also has to
specify the user name to use when connecting to the meta node.
