Add step to check for tag only in scoped messages

[aswaney]

Something similar to:

Then(/^the (?:fix|FIX) messages should include a message with the(?: tag)? "(.*)"$/) do |path|
  expect(@message_scope).not_to be_nil, "No message scope defined"

  found = false
  error_accum = ""
  index = 1
  @message_scope.each do |m|
    @message = m
    begin
      steps %Q{
        When I inspect the #{index}th FIX message
        And the FIX message should have "#{path}"
      }
      found = true
    rescue Exception => e
      error_accum << "\n#{m.to_s.gsub!(/\001/, '|')}\n #{e}"
    end
    index += 1
  end

  expect(found).to be(true), "Tag not included in FIX messages\n #{error_accum}"
end