Log a detailed exception when integration fails (#284)

Author: stewartreichling

opencensus/trace/config_integration.py

@@ -37,11 +37,12 @@ def trace_integrations(integrations, tracer=None):
             module = importlib.import_module(path_to_module)
             module.trace_integration(tracer=tracer)
             integrated.append(item)
-        except Exception:
+        except Exception as e:
             log.warning(
                 'Failed to integrate module: {}, supported integrations are {}'
                 .format(
                     item,
                     ', '.join(str(x) for x in SUPPORTED_INTEGRATIONS)))
+            log.warning('{}'.format(e))
 
     return integrated