Implemented config file reader.
Removed `virtual` destructors.

Virtual destructors are totally not needed here and memory layout
will be improved.
Initial support for networking.
Terminate process in case of socket listen error.
Fixed new client connections.
Implemented reading and writing data over TCP.
Added acceptance tests.

This test executes server and tests it as a "black box" ie.
no assumptions are made to the internals - it should respond
to packets.