#1012812 by myself: filter release list for .tar.gz files to avoid the newly introduced .zip files from breaking package parsing (backport)

#950452 by good_man: clean up CSS slightly and add RTL CSS even if only the l10n_server language is RTL, not the page language; the strings being edited/displayed are RTL in this case, so we need the RTL sheets

 - make front page table include number of contributors per team, 100% wide, tweak headers
 - make top contributors per team a table not a list
 - rename contribute block to jump block, since it allows jumping around in essence
 - remove awfuly updated help blocks (never used on localize.drupal.org)
 - remove exessive text sometimes placed in place of jump box
 - place group board to close to group home
 - remove excessive link of generic download page on pages where we have or lead to downloads directly
 - add more downloads pointer on bottom of team download pages

#966966 followup: cache language specific download tables to speed up page loads and move table headers to actual expanded items

#967704 followup by myself: fix weight columns to be NOT NULL, easier to order by them, we are fine with 0 as the default weight

#967704 by Bojhan and myself: make the main language page more of a download page to be inviting for newcomers

#966966 followup by myself: simplify page even more, add elaboration that this is merely a highlighted project (but drop the extra wrapper that we do not need anymore)

#897118 followup: default project picker for downloads page, so people can jump to project pages / contribution fast

#897118 followup: fixed checked dates to include release check time (file might not be actually regenerated), add in flashy download links

#897118 followup: fixed checked dates to include release check time (file might not be actually regenerated), add in flashy download links

#897118 followup: include update check info in hover text, enable contribute blocks for download page