Added support for defining a custom timeout for injection

This new addon, solved the problem for projects using Backbone with some AMD (like require.js) - where Backbone.js is loaded aftger DOMContentloaded.

This will add a timeout feature to BDT in devTools
![timeout](https://f.cloud.github.com/assets/878660/356358/5802cc64-a103-11e2-9c21-463d1fe9bc86.png)