Add functionality allowing the controller connecting to a switch

OpenFLow 1.3.2 specification introduces a new statement that OpenFlow
controllers can connect to OpenFlow switches actively. Now
the of_controller_v4.sh can be started with an option simulating such
behavior.
(FlowForwarding/LINC-Switch#147).
Introduce config parameter for controllers listener; refactor linc_logic

OpenFLow 1.3.2 specification introduces a new statement that OpenFlow
controllers can connect to OpenFlow switches actively. Config parameter
`controllers_listener` is introduced to support this functionality.
By the way linc_logic module is refactored regarding this functionality.
(FlowForwarding/LINC-Switch#147).
Introduce checking if linc_logic process is alive between linc:start/stop

While running the tests it turned out that linc does not have enough
time to start. Now some checking is introduce to delay stopping the app.
(FlowForwarding/LINC-Switch#147).