improve mechanism for determine appliance's IP address

[alexskr]

current method for determine VA's IP address can be problematic:

• 4store fails to start when user changes hostname from localhost to custom during initial configuration

• unicorn/ontologies_api fails to start when VA is deployed in isolated network.

  require 'socket'
  def local_ip
  orig, Socket.do_not_reverse_lookup = Socket.do_not_reverse_lookup, true  # turn off reverse DNS resolution temporarily
  
  UDPSocket.open do |s|
    s.connect '8.8.8.8', 1 #google
    s.addr.last
  end
  ensure
  Socket.do_not_reverse_lookup = orig
  end

[alexskr]

addressed by https://github.com/ncbo/virtual_appliance/commit/104cd1f95b6aa2fc423bb737057cbdbe30ff1212