Make signalr code run inside ngZone() configurable behavior

[HNeukermans]

Currently all signalr code is run inside a ngzone. This means every signalr callback received triggers a angular change detection.

To allow developer the choice of having it automatically run inside zone.run or to hve more control over when change detection is run we should make this behavior configurable.

something like: configuration.executeEventsInZone configuration.executeErrorsInZone configuration.executeStatusChangeInZone