AVO-157: Extending the support for specifying http headers to the dataSourceFromURL class method.
AVO-157: We can now extract metadata from an icecast stream. Changed the httpheaders class method from previous commit to specifically create an instance of STKHTTPMetadataSource to work along side the previously existing class method instead of complicating things as the changes from the previous commit would have done. Added the copyright message to the top of added files.
AVO-157: Removing logging of metadata message before pushing to repo for distribution to rest of team.