Overriding ServletModule leads to logspam

Simple code line:

`Guice.createInjector(Modules.override(new ServletModule()).with(new ServletModule()));`

Generates misleading warning in log:

> WARNING: Multiple Servlet injectors detected. This is a warning indicating that you have more than one GuiceFilter running in your web application. If this is deliberate, you may safely ignore this message. If this is NOT deliberate however, your application may not work as expected.