Variety 0.8.4

• Remove dead Desktoppr, ChromeOS sources (GH-323)
• Properly verify TLS certificates when downloading images (GH-326)
• Fix banning images when using Delete to Trash option (GH-304)
• Preserve file extensions when copying wallpapers to another folder (GH-240)
• Fix crash in indicator code when image origin is not available (GH-287)
• Remove spurious "No such schema “org.cinnamon.desktop.background” errors" (GH-329)
• Update Unsplash rate limit (GH-332)
• Better detection for AwesomeWM (GH-282)
• Fix blue lockscreen in GNOME, as displaying images there isn't always enabled by default (GH-302)