Main gateway shoud support VSD and EDM format to redirect to responding service

[alja]

Add check in VSD format. Fork should suppose to take less resources. https://github.com/alja/VSDNano/commit/0d8e3b82b06dc7f1befcafe8b2963cacfcaf9efb

Need to make a client request for test in the main gateway:

sub get_data_format
{
  my $file = shift;
  my $port = 5555;
  my $buf = connect_to_server(qq{{"action": "dataformat", "file": "$file"}\n}, $port,1);
  my $resp = eval $buf;
  my $fr = $resp->{'format'};
  return $fr;
}

the test is in the start_session.