Remove deprecated Debug Toolbar configuration option

DEBUG_TOOLBAR_CONFIG.INTERCEPT_REDIRECTS has been deprecated. In fact, the Redirect panel is now disabled by default, so we don't need to define the setting any more.

Deprecation notice: http://django-debug-toolbar.readthedocs.org/en/latest/changes.html#deprecated-features

New default value: http://django-debug-toolbar.readthedocs.org/en/latest/configuration.html#toolbar-options