update wagtailstyleguide and wagtailcore.rich_text to import hooks from wagtailcore rather than wagtailadmin

wagtail/contrib/wagtailstyleguide/wagtail_hooks.py

@@ -4,7 +4,7 @@ from django.core import urlresolvers
 from django.utils.html import format_html, format_html_join
 from django.utils.translation import ugettext_lazy as _
 
-from wagtail.wagtailadmin import hooks
+from wagtail.wagtailcore import hooks
 from wagtail.wagtailadmin.menu import MenuItem
 
 from wagtail.wagtailimages import urls

wagtail/wagtailcore/rich_text.py

@@ -13,7 +13,7 @@ from wagtail.wagtaildocs.models import Document
 from wagtail.wagtailimages.models import get_image_model
 from wagtail.wagtailimages.formats import get_image_format
 
-from wagtail.wagtailadmin import hooks
+from wagtail.wagtailcore import hooks
 
 
 # Define a set of 'embed handlers' and 'link handlers'. These handle the translation