replacing feedback link with About Piwik page giving us the possibility to write more about piwik and remove header message at least for non admin users. There is a lot of room for improvments
added footer from website, social icons still missing, maybe we better remove the menu links
switched privacy link with blog
added social icons to about piwik page
About Piwik -> Help
fix update check and some header message display issues
do not underline check for updates link by default
smaller font size
made the help even smaller
increased gap above social buttons
simplify and make sure to display only to superusers or piwik demo users
Merge branch 'master' into about_piwik_page_experiment

Conflicts:
	lang/en.json