vimrc: Use tmux filetype and syntax plugin bundle.
vimrc: Don't use Command-T.
vimrc: Show hidden files when using Ctrl-P.
Add tmux.conf as tmux configuration file.
tmux.conf: Change prefix, use 256 color terminal.
Remove Command-T references.
zshrc: Use conditional checks for rbenv and powerline.
zshrc: Add vagrant completion and path.