Issue/1730 reader detail infinite scroll with blocking

Fix #1675 and fix #1730 - adds "infinite" scroll to the reader detail ViewPager and adds the ability to block a blog from the same view. This was initially submitted as separate PRs, but they rely so heavily on each other that it made more sense to combine them.
In this case I was mimicking the web reader, but I *think* the reason for this is because blocking is really intended as a way to get rid of annoying/irrelevant blogs in followed tags, where no private posts would be. Plus, if you follow a private blog it's unlikely to be one you'd want to block.

I admit to not liking the inconsistency, though.