resultForDeactivate and resultForActivate are set to null in some situations in Android plugin

[ikbalkaya]

Problem
{{resultForDeactivate}} and {{resultForActivate}} are set to null (sometimes, in some devices) that resulted customer reported crashes happening. See
#298

Suspected cause
{{PushActivationEventHandlers}} class has a declared inner broadcast receivers that access to {{resultForActivate}} and {{resultForDeactivate}} on {{onRecieve}} method. However it's possible (?) that PushActivationEventHandlers is disposed while broadcast receiver still receives messages (most probably on background).

[ikbalkaya]

I did some tests to confirm whether broadcast receiver can exist in absense of PushActivationEventHandlers. Looks like it's the case. Setting up the PushActivationEventHandlers instance or any of its instance variables to null won't affect the ability for broadcast receiver to receive messages.