Add a script generating a config file for the LINC

The `config_gen` generates a config file for the LINC-Switch. It allows
to specify logical switches and its interfaces along with the output file.
(Motivated by #129).
Add scenario sending table_miss flow mod

The flow mod makes the switch to send all not matching packets to the controller
(Motivated by #129)
Merge pull request #140 from FlowForwarding/issue129

Add utility for generating LINC config and a scenario sending table_miss