Modified browser.js and logger.js

This PR has two tweeks which make it possible to run montage in a sandbox in a chrome app.

* workaround for inability to read files from the app: you can use postMessage to ask the app to load files and pass their contents back to the sandbox where you can use them. 
* try catch for security exception for trying to use localstorage (it looked like it was already optional)

these might not be necessary, but for now they make it so a montage app can be run in a chrome app