Merge RAPPS improvements branch into trunk.

Contains the work done by sanchaez (Alexander Shaposhnikov) during GSoC 2017:
 * Better information in the application details view.
 * Bulk installation of multiple applications at once.
 * Command-line automation of installation (single and bulk).

(for more details, see the related blog posts)

TRANSLATORS: Many resources have been changed, and they are in need of review!

svn path=/trunk/; revision=75826