add network activity indicator

[mbap]

UIApplication *app = [UIApplication sharedApplication];
this will return the shared application.

has a property called network activity indicator that needs to be turned on when the app makes network calls. in addition this must be managed by us.

for example if 2 objects are making network calls we need a variable that keeps track of the number of people making calls. we only turn this off when it goes back to zero.