Add configuration for adding FIX tag to output hash keys

[daino3]

current:

{
  "BeginString" => "FIX.4.2"
  "MsgType" => "NewOrderSingle"
}

could add a configuration to add tag numbers:

  # config
  fix_protocol {
    fix_message => fix_string
    include_tags => true # new config
    session_dictionary_path => "/vagrant/spec/fixtures/FIXT11.xml"
    data_dictionary_path => "/vagrant/spec/fixtures/FIX50SP1.xml"
  }

Which would generate new hash keys:

{
  "BeginString (8)" => "FIX.4.2"
  "MsgType (35)" => "NewOrderSingle"
}