Add tmux keybinding for clearing scrollback buffer
Add tmux keybinding for clearing scrollback buffer

Doing `<prefix> Ctrl-k` will now clear the current tmux window's
screen and scrollback buffer.

Adapted from
http://notes.jerzygangi.com/the-only-way-that-actually-works-to-clear-the-screen-in-tmux/.

kjhaber/dotfiles