New metrics logger system

- It's not mandatory to have the log_path defined for all the services
- Now we add metrics to a MetricsGatherer using the add method in order
  to gather data from all the function scope, not just in one defined
  point
- There is a `metrics` context manager to wrap the function block. This
  context manager get the execution time for the block among other
  things

server/lib/python/cartodb_services/setup.py

@@ -10,7 +10,7 @@ from setuptools import setup, find_packages
 setup(
     name='cartodb_services',
 
-    version='0.9.4',
+    version='0.10.0',
 
     description='CartoDB Services API Python Library',