Create structure and append gitignore for latest workbench.

.gitignore

@@ -5,6 +5,8 @@
 /workbench.*
 /dist
 /templates
+/var
 *.iml
 .idea/*
+dump.rdb
 problem_builder.tests.*

run_tests.py

@@ -24,6 +24,12 @@ if __name__ == "__main__":
     # Configure a range of ports in case the default port of 8081 is in use
     os.environ.setdefault("DJANGO_LIVE_TEST_SERVER_ADDRESS", "localhost:8081-8099")
 
+    try:
+        os.mkdir('var')
+    except OSError:
+        # May already exist.
+        pass
+
     from django.conf import settings
     settings.INSTALLED_APPS += ("problem_builder", )