- Found a case that if you slow down sse transport then both transports
will be active causing a number of issues. Looks like we found that
before
- added completion block to see negotiate as well for #276

- by default you should not be messing with transport on the
connection. we needed to for our use case and I could not figure out
another way to get access to this other than exposing it.

- sse will continue reconnecting even if the connection is no longer
referencing the transport if you use it directly. dereference
everything so that it will not attempt to reconnect after being stopped

- when testing if you either timeout or abort connections (using
fiddler or some other mitm tool) on most connections, they fallback
regularly, but if you ever get to longPolling, it would continue
retrying forever - even if there no connection ever comes up. This
change checks if we are active when it gets an error in longPolling. If
outside the reconnectWindow, it will stop the connection.

- 503 errors or firewall software, etc will hit the
NSStreamEventOpenCompleted and thus the onOpened callback. But we do
not want to trigger didReconnect here or else we’ll never timeout our
reconnect. Instead, process the initialized message that is sent down.

- the bool was not always catching our reconnect and was a little more difficult to track what was going on. Instead store the blockoperation and cancel in the right places

- left out an important change for 300: moving the reconnect logic
exclusively to the message + initialized loop. prior code didn’t
actually change anything