Multiplex ws allow duplicate messages to be filtered

[AdamMagaluk]

Adds filterMultiple query parameter to multiplexed ws. If filterMultiple is set as a query parameter on WS /events then all events that fulfill multiple subscriptions will only be sent once to the client. The subscriptionId will always be an array of subscriptions it fulfills.

Eg.

Without filterMultiple subscribing to ** and */photocell/*/intensity

λ: wsta ws://localhost:1337/events '{"type": "subscribe", "topic": "**"}' '{"type": "subscribe", "topic": "*/photocell/*/intensity"}'
Connected to ws://localhost:1337/events
{"type":"subscribe-ack","timestamp":1467138805442,"topic":"**","subscriptionId":1}
{"type":"subscribe-ack","timestamp":1467138805442,"topic":"*/photocell/*/intensity","subscriptionId":2}
{"type":"event","topic":"milford/photocell/e7ffb5e3-6961-4d03-8eca-e4267c49af5a/intensity","timestamp":1467138805468,"subscriptionId":1,"data":1.258819045102531}
{"type":"event","topic":"milford/photocell/e7ffb5e3-6961-4d03-8eca-e4267c49af5a/intensity","timestamp":1467138805468,"subscriptionId":2,"data":1.258819045102531}

With filterMultiple subscribing to ** and */photocell/*/intensity

λ: wsta ws://localhost:1337/events?filterMultiple=true '{"type": "subscribe", "topic": "**"}' '{"type": "subscribe", "topic": "*/photocell/*/intensity"}'
Connected to ws://localhost:1337/events?filterMultiple=true
{"type":"subscribe-ack","timestamp":1467138861241,"topic":"**","subscriptionId":1}
{"type":"subscribe-ack","timestamp":1467138861242,"topic":"*/photocell/*/intensity","subscriptionId":2}
{"type":"event","topic":"milford/photocell/e7ffb5e3-6961-4d03-8eca-e4267c49af5a/intensity","timestamp":1467138861259,"subscriptionId":[1,2],"data":0.9999999999999961}

Also includes fixes to allow device queries on remote peers to work over multiplexed ws.

Device queries come in the format {serverName}/query/{query string}

[mdobson]

+1

[mdobson]

+2