SupportVersionFinder and MasterVersionFinder are too equal in content

[GeertvanHorrik]

The content of both files is nearly identical, and should be put into a shared class where only the word "support" differs from "master" in 2 places. I am currently working on a pull request and don't want to do this in the same commit to keep it as clean as possible, but I think this should be fixed.

[JakeGinnivan]

All this code is gone in 3.0 :)