Add android.app.Service to whitelisted Android initializer classes.

Summary:
It has a similar lifecycle to activities and fragments, it would be nice to support `onCreate` as an initializer by default.
Closes https://github.com/facebook/infer/pull/258

Reviewed By: jeremydubreil

Differential Revision: D2887325

Pulled By: cristianoc

fb-gh-sync-id: ed31df5

infer/src/checkers/patternMatch.ml

@@ -234,6 +234,7 @@ let initializer_classes =
       "android.app.Activity";
       "android.app.Application";
       "android.app.Fragment";
+      "android.app.Service";
       "android.support.v4.app.Fragment";
     ]