Implement checking that listen sockets from Tempesta FW configuration is not used

[EvgeniiMekhanik]

Motivation

Currently if administrator chooses in the configuration the listen addresses that are already in use by other process, Tempesta FW fail to start. Moreover if Tempesta is already work it will be stopped. For better usability it will be good to check that sockets from configuration is not already used by other process.

What should be done

There are a lot of ways to specify listen address in Tempesta config, so the best way to solve this task is to write small python script, which will use regular expressions to parse Tempesta config and check if this addresses are in use. This script should be called from tempesta.sh and if returns error, Tempesta loading should be cancelled.

[krizhanovsky]

This task is separated from #2017 and #2043 addressed in pull request #2045