Refactor the setup of Shill*Stubs' default environment.

This change untangles some of the Shill*Stubs' implementation from the setup of a default network environment. In particular the setup function has now access to all Shill*Stubs during this setup.

This also correctly adds stub networks with status 'online' to a profile, so that the respective FavoriteState is created.

BUG=126870
R=stevenjb@chromium.org

Review URL: https://codereview.chromium.org/24150004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@224756 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 224756