WIP: post: Dropping old TLS on Android

This is a post describing some work I'm doing right now to drop support for TLSv1.0 and TLSv1.1 in the client. They are old, broken, and already have been dropped in many places. The major browser vendors have promised to drop them in 2020, and there is an IETF draft that will likely become standard that will officially deprecate them. This would take affect in F-Droid 1.8, which would probably be released at the end of July or August.

@All since this means potentially dropping support for some old repos that do not support TLSv1.2, I wanted to get everyone's approval before launching.