Improve Vim's Vundle update task (quieter)
Use Homebrew Cask to install applications

Add:
 * Ability to install brew-cask when installing brew packages
 * Task to install brew cask packages, and included in install task
 * A bunch of brew cask packages to be installed
 * Environment variable to speicfic the default location for brew cask
   to be installed in, which in this case is the /Application directory
 * Changes required for the diff/merge tools in sourcetree (gitconfig)

Refactor:
 * Macvim to be installed as an application vs. brew