Fix rabbit source

- Fixed rabbit source's connectionFactory to read as "rabbitConnectionFactory"
- Added rabbit.properties under ${xd.config.home}
Fix rabbit source/sink

- Fix config/rabbit.properties to have default values
- Set rabbit sink's 'cloud' profile connection factory to read
  'rabbitConnectionFactory'
Fix typo on property
Added username and password to RabbitSourceOptionsMetadata - WIP

The values aren't applied, needs investigation