Gossip re-orders header and URI params

[StefanKopieczek]

• If we are acting as a transparent proxy, we may reorder header params and URI params when we forward messages.
• Gossip processes header and URI params in an undefined order.
• String representations of SIP messages received by gossip may show params in a diferent order to that received off the wire.

This is because the Params object that stores them holds them in a map, which doesn't have a defined iteration order.

Fixer should uncomment the broken stringify tests.

[StefanKopieczek]

I think this is a dupe of your issue #3. Close of you agree.

[rynorris]

Yes.