Configure vimdiff as git mergetool
Revert "adding a check for git config option to disable git_prompt_info() on a per repo basis"

This reverts commit fbd479b68e2c58068666f738a009ef7a1ca8abde.

Usually we use oh-my-zsh.hide-status=1 because it's too slow to check
dirty flag for big project (e.g. linux kernel) every time the prompt is
displayed. However is usefull (and less time consuming) display the
current HEAD