Tests: minor improvements.

Added "go" availability check before trying to build an application.

update_action() method used were possible and fixed bug with
the relative path determination in test_static_chroot.py.

Templates optimization and style fixes.

test/unit/applications/lang/go.py

@@ -9,6 +9,11 @@ from unit.option import option
 class TestApplicationGo(TestApplicationProto):
     @staticmethod
     def prepare_env(script, name='app', static=False):
+        try:
+            subprocess.check_output(['which', 'go'])
+        except subprocess.CalledProcessError:
+            return None
+
         temp_dir = option.temp_dir + '/go/'
 
         if not os.path.exists(temp_dir):