Feature: added new parameter to rabbitmq river

rabbitmq river has a new parameter which sets the binding of the queue.
"queue_bind" can so bet set to true or false and default: True.
Merge pull request #297 from julianhille/master

Added new rabbitmq river config parameter queue_bind
Merge pull request #296 from CGenie/cgenie

Add 'existence' and 'null_value' options for MissingFilter
JDBC River: default for sql parameter is an empty string