pass the voiceBridge parameter to BBB create; fixes #5031

Change-Id: I5af40fa6237f5a39e562a35fb49b53cff6e33b41
Reviewed-on: https://gerrit.instructure.com/5033
Reviewed-by: Brian Palmer <brianp@instructure.com>
Tested-by: Hudson <hudson@instructure.com>

app/models/big_blue_button_conference.rb

@@ -33,6 +33,7 @@ class BigBlueButtonConference < WebConference
     send_request(:create, {
       :meetingID => conference_key,
       :name => title,
+      :voiceBridge => self.id.to_s,
       :attendeePW => settings[:user_key],
       :moderatorPW => settings[:admin_key],
       :logoutURL => (settings[:default_return_url] || "http://www.instructure.com")