Add possibility to use private key for accessing gerrit

Change-Id: I551c6b4baf942e096dc0b8f13bde05be7657b84f
diff --git a/tcp_tests/helpers/utils.py b/tcp_tests/helpers/utils.py
index f2311d4..480a646 100644
--- a/tcp_tests/helpers/utils.py
+++ b/tcp_tests/helpers/utils.py
@@ -356,6 +356,12 @@
 
         return var
 
+    def basename(path):
+        return os.path.basename(path)
+
+    def dirname(path):
+        return os.path.dirname(path)
+
     if options is None:
         options = {}
     options.update({'os_env': os_env, })
@@ -366,6 +372,9 @@
     environment = jinja2.Environment(
         loader=jinja2.FileSystemLoader([path, os.path.dirname(path)],
                                        followlinks=True))
+    environment.filters['basename'] = basename
+    environment.filters['dirname'] = dirname
+
     template = environment.get_template(filename).render(options)
 
     if required_env_vars and log_env_vars: