add config file to test function evaluator

cfg/test_function_cfg.py

@@ -0,0 +1,15 @@
+Node('softcal.function.test',
+    'test the function class',
+    'tcp://5000',
+)
+
+Mod('sim_writable',
+    'frappy_demo.test.SimpleWritable',
+    'simulation of a writable for function test',
+)
+
+Mod('function',
+    'frappy_psi.softcal.Function',
+    'function test',
+    rawsensor = 'sim_writable',
+)