v2.10.9 RSS feed reader release

NEW this release:

• RSS feed reader (#219)
• enhanced cache control for static assets (#221)
• optimized album detail retrieval (#218)

This release also contains a roll-up of the following hotfixes:

• websockets silently disconnect after inactivity (#209)
• ExportPlaylist::extractTime filter is too aggressive (#210)
• OnNowFilter::peek ignores optional type filter (#211)
• non-music entries in push feed are not accounted for (#212)
• push notifications are being delivered for unpublished playlists (#213)
• long titles wrap home page 'On Now' (#215)
• playlist fields are not scrubbed for length (#216)
• handleAddTrack's test for insert failure is too strict (#217)