* Fixed places where IO was done on main thread
* Created reactive class Observable so that work could easily be done on
other threads
* Fixed potential NPEs in LightningView
* Fixed memory leak where ConnectivityManager was leaking activity
Previous AsyncTask would throw a RejectedExecutionException if too many
AsyncTasks got spawned on the thread pool executor. The solution was to
create a custom Executor that properly executed the task and queue it if
necessary. Also switched to using weakreference for the view and set
timeouts on image loading so it can load faster.
