This prevents conversion of QByteArray to QString from truncating content at a null byte in the QByteArray. This truncation can be a problem if the response body is a binary object (e.g. PDF)
Fixes#322
If I use pushState to change the URL Browser#current_url still returns
the URL as it was after the original request. This commit adds a command
for RequestedUrl, which is the QtWebkit method for retrieving a URL
modified by Javascript or a redirect.