Prevent multiple calls to notifications API when changing fragments

Fix multiple bugs

This reverts commit 65868c83.

This fixes reflow on image load

1. Older articles showed up on refresh, since the existing buffer was
not cleared
2. Same articles would show up sometimes while scrolling since order of
loading was not guaranteed.
3. Repetitive calls were being made when the user reached bottom, making it
unreadable due to too many re-renders (also related to 2)

Since this is a very expensive call, the data to be loaded in the
fragment has sluggish response when made in parallel to this call.

Download images on background thread in sync, fix notification image cache

Update dependencies, make support libraries consistent