refactor(superdesk): introduce superdesk.menu module

Makes menu/notifications opening using model which is shared
via parent directive controller.
fix(media): replace img on load to prevent 0.5 opacity
feat(analytics): add analytics tracking

this is an initial test of analytics in the app.
we want to see what info we can get from it.
fix(analytics): fix template task with ga tracking id
fix(media): add info about recently added items

SD-267
fix(media): fix several styling issues
fix(upload): resend upload requests on 401 response

SD-273
refactor(activity): minor refactoring and tests.
fix(media): add styles for media preview action buttons
clear unused styles and images
get rid of custom.css file

remove unused styles from custom.css
copy used parts in other relevant files
make close button look consistent

+ modal close
+ pane close
+ view close
remove old avatar upload scripts
make topnav action buttons consistent
feat(analytics): add support for piwik tracking

SD-274
doc(analytics): add info how to setup analytics

SD-274