Simplify aos::Init

Most of the variants were to deal with core, which has been gone for a
year.  Simplify those all into InitGoogle.

InitGoogle should be renamed to Init at some point.  It does everything
now.

Change-Id: I738ee03e9c5b2e6348ef33302835f915df68011f
diff --git a/aos/input/joystick_input.h b/aos/input/joystick_input.h
index 7a6e8c3..aceda52 100644
--- a/aos/input/joystick_input.h
+++ b/aos/input/joystick_input.h
@@ -22,7 +22,7 @@
         "/aos", [this](const ::aos::JoystickState &joystick_state) {
           this->HandleData(&joystick_state);
         });
-    event_loop->SetRuntimeRealtimePriority(29);
+    event_loop->SetRuntimeRealtimePriority(28);
   }
 
  protected: