Install casks via Caskfile

`brew bundle` can now be used for casks as well.

Closes #365.
Brewfile: Install GNU `sed`
Brewfile: Install some more useful tools
.functions: Make `gi` accept any number of arguments

Closes #367.
Merge remote-tracking branch 'upstream/master'

* upstream/master:
  .functions: Make `gi` accept any number of arguments
  Brewfile: Install some more useful tools
  Brewfile: Install GNU `sed`
  Install casks via Caskfile

Conflicts:
	.cask
	Brewfile