add template folder CRUD

* create template folder
* rename template folder
* get list of template folders for service (not nested/presented in any
  particular way)
* delete template folder

Also removed `lazy=dynamic` from the `template_folder.templates`
relationship. lazy=dynamic returns a query object (which you can then
filter further). We just want to return the entire fetched list, at
least for now.

app/dao/template_folder_dao.py

@@ -0,0 +1,22 @@
+from app import db
+from app.dao.dao_utils import transactional
+from app.models import TemplateFolder
+
+
+def dao_get_template_folder_by_id(template_folder_id):
+    return TemplateFolder.query.filter(TemplateFolder.id == template_folder_id).one()
+
+
+@transactional
+def dao_create_template_folder(template_folder):
+    db.session.add(template_folder)
+
+
+@transactional
+def dao_update_template_folder(template_folder):
+    db.session.add(template_folder)
+
+
+@transactional
+def dao_delete_template_folder(template_folder):
+    db.session.delete(template_folder)