[MRG+2] added BLOCKING_FEED_STORAGE_PATH to settings #1847
I'm adding a new setting BLOCKING_FEED_STORAGE_PATH to configure a folder used to save temporary files before uploading them.
This setting defaults to None and will pick a system temporary folder. If a value is set, will raise an exception if it's not a valid directory and use it otherwise.
See #1779 for more details