Ignore .ruby-version as well as .rbenv-version

They're synonymous now.
Reverting "Add "FactoryGirl.build_stubbed" back in"

This is still causing segfaults on Jenkins. Since this is a
non-deterministic failure I can't really begin investigating right now.

This reverts commit b4a6031dc7fbe604cb98e362de9ea5c51dcf5930.