Expose the type of receiver against the session

[dombenson]

This is useful for diagnostics or logging when fallback mechanisms are in use

[coveralls]

Coverage decreased (-1.2%) to 93.29% when pulling ad4c80a on dombenson:expose-receiver-type into cd6986d on igm:master.

[FZambia]

The implementation looks not thread-safe, also I think that for debugging purposes it's enough to just use session.Request().URL.Path

Maybe In general the helper like this could be useful but in my opinion it must also distinguish HTTP fallback type used - i.e. xhr-streaming, eventsource etc.

[igm]

fixed in v3