provides autocompletion for artisan.
…'t say yes, it won't ask them again for a while. fixes #1240
Evaluates $(rbfu --init --auto) if rbfu is installed on the system, also has a custom rbfu-rubies method which lists the installed rubies which are available to rbfu. For compatibility with themes, also creates the rvm_prompt_info function, so existing themes should work out of the box.