Use injector for Ansel_Storage.

Use injector for Ansel_Storage.

Introduces a new Ansel_Config class for setting ansel config values that
might change during runtime, such as $scope.  The Ansel_Storage factory uses
Ansel_Config from the injector to return the proper storage scope. So, to
use a scope other than the default 'ansel' scope, you need to set it as:

$GLOBALS['injector']->getInstance('Ansel_Config')->set('scope', 'foo');