Add .sublime-project file to easily open this project

The Dart.sublime-project file also includes basic settings that
should help keep new files' characteristics like newlines and
trailing whitespace unified.

Although these issues may be handled by a format command in the
Dart sdk or a VCS like git, I think it won't hurt to add them here
too.
Remove global settings from .sublime-project file.
Merge pull request #61 from guillermooo/sublime-admin

Add .sublime-project file to easily open this project in Sublime Text