Revert "Added my prompt theme, with a tweak to the core oh-my-zsh to support it. My git_prompt_info function not only reports the branch and dirty status, but also whether or not the branch is ahead or behind of the remote, or both. It also switches the prompt colour from green to red if the previous command exited with a non-zero value (i.e. failed)."

This reverts commit 14a1ce80.