Enable default database for _connect()

In the event you connect with a user that doesn't have it's own
database, set the default to be 'postgres' to enable _get_db_names()
to be able to collect the list of databases.
Adding the ability to set keepaliveinterval and atempt socket reconnect
on exception in _send_data
Merge pull request #461 from peterkh/master

Adding the ability to set keepaliveinterval and attempt socket reconnect on exception in _send_data
Merge pull request #459 from jbouse/feature/postgres-defaultdb

Enable default database for _connect()
Adding DRBD collector
Merge pull request #467 from faridsaad/drbd_collector

Adding DRBD collector