R1:c9c4dc1d9b01

Config - add setup checks for minimum and "bad" versions of VCS software.

Summary: Fixes T3046. Git has no minimum or bad versions; svn has no minimum and the bad version of 1.7.1, and mercurial has a minimum of 1.9 and bad versions 2.2 and 2.1. These error messages are specific about the problem but do not include the details as to what specifically is bad about a given version. I don't think that's really necessary - the details don't help solve the problem and its probably booooooring at best to the…