Git: ignore IntelliJ project files/directories
Command-T: pwd knows best; don't look for a SCM root
Remove no-longer-used vim-rvm plugin

I'm rolling with rbenv these days.
Use plain, default Powerline settings for now

After (long-overdue) updating my installed plugins, Powerline started
failing miserably due to backwards-incompatible changes. I'll review any
settings later; it's more important to have a working editor at the
moment.