Enable iTerm integration with TMUX.

OSX iTerm2 Integration

iTerm2 offers significant integration with tmux. This can be enabled by adding the following line to zpreztorc:
zstyle ':prezto:module:tmux:iterm' integrate 'yes'

See more information on iTerm2 and tmux integration on the following pages:
http://iterm2.com/downloads.html
https://code.google.com/p/iterm2/wiki/TmuxIntegration