Module monitor rethinkdb health metrics.

Following charts are drawn:

1. Connected Servers

• connected
• missing

2. Active Clients

• active

3. Queries per second

• queries

4. Documents per second

• documents

localhost:
  name     : 'local'
  host     : '127.0.0.1'
  port     : 28015
  user     : "user"
  password : "pass"

When no configuration file is found, module tries to connect to 127.0.0.1:28015.