Put the (pull request repo owner) branch and commit in Appveyor EXE names
For pushes to our repo and pull requests from the same repo (if that ever happens): Linking srb2win-appveyor-exename-70cf119a.exe...
For pull requests from a fork: Linking srb2win-jameds-appveyor-exename-470d00a8.exe...
Edited by James R.