Extend reload support to download with QNetworkRequest

If the QNetworkRequest has a CacheLoadControlAttribute
of AlwaysNetwork, set the reload flag for a download
and queueDownload request.
Extend reload support to post with QNetworkRequest

If the QNetworkRequest has a CacheLoadControlAttribute
of AlwaysNetwork, set the reload flag for a post
and queuePost request.  While posts are usually not
cached, the RFCs allow it in specific cases.  This
allows the caller to request no cache processing.
Request AlwaysNetwork if m_reload is set for the request

If m_reload is true, request that Qt actually performs
similiarly to a browser reload (bypass and reload any
cache).
Convert the ceton tuner from using QHttp to MythDownloadManager

This changes the cetonstreamhandler code from using QHttp
to MythDownloadManager.  This is needed for Qt5, but is
backwards compatible for the current Qt4.8 distributions.