Stubbed runtime and app.runtime in caterpillar.js. Resolves #8.

src/caterpillar.py

Index: src/caterpillar.py
diff --git a/src/caterpillar.py b/src/caterpillar.py
index b9442336560385f26f5792c1ce8ff66dcb1fbead..1e78ffdb595214df6b2bb791950bad9d8560fe9f 100755
--- a/src/caterpillar.py
+++ b/src/caterpillar.py
@@ -103,16 +103,6 @@ var CACHED_FILES = [
 importScripts('{boilerplate_dir}/caterpillar.js');
 importScripts('{boilerplate_dir}/sw_static.js');
 
-// Ignore calls to chrome.app.runtime.onLaunched.addListener from the background
-// scripts.
-chrome.app = {{
-  runtime: {{
-    onLaunched: {{
-      addListener: function() {{}}
-    }}
-  }}
-}};
-
 // TODO(Caterpillar): Edit background scripts to remove chrome.app.runtime
 // dependence.
 """