Module loader: removed deprecated option sameGroupAs for sandboxes

This option has been removed monthes ago. See https://bugzilla.mozilla.org/show_bug.cgi?id=722775
Fixes an issue: modules should have access to global objects

Modules in PhantomJS have access to the window, document and
phantom objects, that are available in the main script.

Modules in SlimerJS should have same access.
Module loader: removed some hacks from the addons-sdk loader