collections: add support to browse existing collections

- add a route at /u/<user>/collections/ (note trailing 's') that lists
  all existing collections
- move there the "Create new collection" link, if the user is logged in
- add a new link "Browse collections" from root.html

mediagoblin/user_pages/routing.py

@@ -48,6 +48,10 @@ add_route('mediagoblin.user_pages.media_collect',
           '/u/<string:user>/m/<string:media>/collect/',
           'mediagoblin.user_pages.views:media_collect')
 
+add_route('mediagoblin.user_pages.user_collections',
+          '/u/<string:user>/collections/',
+          'mediagoblin.user_pages.views:user_collections')
+
 add_route('mediagoblin.user_pages.user_collection',
           '/u/<string:user>/collection/<string:collection>/',
           'mediagoblin.user_pages.views:user_collection')

mediagoblin/user_pages/views.py

@@ -337,6 +337,23 @@ def user_collection(request, page, url_user=None):
          'pagination': pagination})
 
 
+@active_user_from_url
+@uses_pagination
+def user_collections(request, page, url_user=None):
+    """A User-defined Collection"""
+    collections = Collection.query.filter_by(
+        get_creator=url_user)
+
+    pagination = Pagination(page, collections)
+
+    return render_to_response(
+        request,
+        'mediagoblin/user_pages/collections.html',
+        {'user': url_user,
+         'collections': collections,
+         'pagination': pagination})
+
+
 @get_user_collection_item
 @require_active_login
 @user_may_alter_collection