initial JS support

just the basis, reload implemented by using protocol.evaluate
some side effects found when reloading and the edited document
is not the live HTML document. (editor = null at getResponseData())
disable code that prevents reloading the page

detachingFromEditor being executed in close handler and
in activeEditorChange handler prevents HTML instrumentation when
reloading the page since they make editor = null at getResponseData.

(temporarily commented until open issues of life cycle be implemented)
Merge pull request #9 from sebaslv/js-app-reload

Support for JS files (page reload after modifications)