optimized google finance query

* used the new method and URL to query quotes from google, which
includes more information than the previous version, such as days
low/high.
* updated the manifest "content_security_policy" to allow the new URL
http://www.google.com/finance/info (which used to be
http://finance.google.com/finance/info).
* also don't forget to change the URL to make it https, otherwise it
won't work.