Version 3.21.4
~~~~~~~~~~~~~~
Released: 2016-07-18

This is an unstable release in the 3.21 development series, with the following
improvements:
 * Add a cancel button and progress information to the details page
 * Add a dialog to confirm upgrade removals
 * Add support for authenticating in plugins
 * Add support for snaps
 * Enable gtk-doc generation for documentation
 * Show a new-style category list on the overview page
 * Show origin information when applications are available from multiple
   sources
 * Show sandboxing information for selected applications
 * Show the star ratings in more places
 * Support installing .flatpakrepo files
 * Support launching applicatins using a appstream:// URL

The following bugs are also fixed:
 * Allow plugins to be enabled and disabled at runtime
 * Always show the 'MyLanguage' kudo when in en_US locale
 * Correctly trigger systemd offline updates when only processing OS updates
 * Disable app folders feature when run outside GNOME
 * Do not show buttons on the search results
 * Do not use deprecated CSS properties
 * Do not use deprecated fwupd API
 * Ensure reviews are shown in the correct order
 * Fix a crash when double clicking files
 * Fix several UX issues when upgrading
 * Show the 'More Reviews' button in the details panel
 * Try really hard to have two rows of important categories

This release also updates translations.