Updating README to describe Package Control installation instructions.
Updating README to describe Package Control installation instructions.

guillermooo-forks/dart-sublime-bundle,guillermooo/dart-sublime-bundle,guillermooo-forks/dart-sublime-bundle,guillermooo/dart-sublime-bundle,guillermooo/dart-sublime-bundle,guillermooo-forks/dart-sublime-bundle,guillermooo-forks/dart-sublime-bundle,guillermooo/dart-sublime-bundle