Add Multisite Commands

[majick777]

To add support for Multisite installs, new sitewide commands:

• networkactivateplugin, networkdeactivateplugin

And the following existing commands are disabled for multisite in 1.0.4 and will need to support being provided an extra Site Blog ID parameter to work:

• activateplugin, installactiveplugin, deactivateplugin
• checktheme, activatetheme, installactivatetheme

And deletetheme will need to prevent delete of any active parent/child themes.