Fix toggleLocationTracking logic

Fixed an issue where toggleLocationTracking wasn't saving the correct setting value.  

Please note that there is a bug in Ionic where ng-click fires twice upon clicking a link/button.  It appears that this issue only occurs in development (ie., emulator) but we need to confirm that's really the case once we deploy our app to an actual device.

cc: @jjmerino, @kmeurer, @jamesongamble, @suprbh