Remove jcenter, update Android bits?

[Cervator]

This repo is not very active and badly needs some dusting off, but that isn't priority right now unless somebody appears out of nowhere with some enthusiasm to fix all the things.

But just so we don't lose track of some things jcenter is going away which means we need to remove it from build files (usually just replace with Maven Central if not present already). With Android bits involved it can be a little trickier as only new versions of some stuff exist in Maven Central. I'm not sure how deep this repo goes in Android land but I saw a few related files and wanted to link to MovingBlocks/DestSolAndroid#18 as an example of what can be done to clean up.

[Cervator]

Replace jCenter in all repositories