added links to supervisors
use wagtailcore_tags instead of deprecated rich_text tag library
Fix ResearchStudentIndex.route to return a RouteResult
Fix GalleryPage.route to return a RouteResult
Update NewStudentPage to use preview_modes / serve_preview rather than get_page_modes / show_as_mode
Version-bump wagtail, south and psycopg in requirements.txt; add migration to apply wagtail0.5 image updates on our custom image model
reinstate gunicorn in requirements.txt, because it's included in INSTALLED_APPS
Merge branch 'wagtail0.5' into develop