Warn user if DB not up to date, in new table wizard

also start adding 'dirty' page behavior, to warn user if navigating
away that changes will be lost

also improve steps in wizard, so page header is scrolled into view
when prev/next buttons are clicked.  unfortunately it still does not
work right if user clicks the step number on left of screen..

tailbone/views/tables.py

@@ -194,6 +194,8 @@ class TableView(MasterView):
         app = self.get_rattail_app()
         model = self.model
 
+        kwargs['alembic_current_head'] = self.db_handler.check_alembic_current_head()
+
         kwargs['branch_name_options'] = self.db_handler.get_alembic_branch_names()
 
         branch_name = app.get_table_prefix()
@@ -331,6 +333,11 @@ class TableView(MasterView):
 
         return HTML.tag('span', title=text, c="{} ...".format(text[:max_length]))
 
+    def migrations(self):
+        # TODO: allow alembic upgrade on POST
+        # TODO: pass current revisions to page context
+        return self.render_to_response('migrations', {})
+
     @classmethod
     def defaults(cls, config):
         rattail_config = config.registry.settings.get('rattail_config')
@@ -348,6 +355,17 @@ class TableView(MasterView):
         url_prefix = cls.get_url_prefix()
         permission_prefix = cls.get_permission_prefix()
 
+        # migrations
+        config.add_tailbone_permission(permission_prefix,
+                                       '{}.migrations'.format(permission_prefix),
+                                       "View / apply Alembic migrations")
+        config.add_route('{}.migrations'.format(route_prefix),
+                         '{}/migrations'.format(url_prefix))
+        config.add_view(cls, attr='migrations',
+                        route_name='{}.migrations'.format(route_prefix),
+                        renderer='json',
+                        permission='{}.migrations'.format(permission_prefix))
+
         if cls.creatable:
 
             # write model class to file