Revert "Git v2 already defaults to push.simple, so dont set it explicitly because Cygwin git v1.7.9 complains "Whats push.simple mean""

Without explicity setting push.simple, then git warns us on every git
invocation about the new push workflow.

I don't want that warning every time, so must set push.simple explicitly.

This reverts commit dea524e818edc3e312d01f1cc49182c2485ff0fd.