notifications: Drop the dep on libgnome-menu

This removes a leftover configure check on libgnome-menu-3.0. The gmenu
APIs were only ever used in the WIP notification panel patches in
https://bugzilla.gnome.org/show_bug.cgi?id=685928 , but the final code
that landed used equivalent gio API instead.
privacy: add first integration with metrics service

Still not wired in.

[endlessm/eos-shell#2728]
display: adjust output thumbnail to bottom panel

[endlessm/eos-shell#2741]
Merge pull request #7 from endlessm/shell/2741

display: adjust output thumbnail to bottom panel
Merge pull request #6 from endlessm/shell/2728

privacy: add first integration with metrics service
cc-util: add a function to get vendor-prefixed app infos

We're going to use this from the Notifications and Search panels.

[endlessm/eos-shell#2756]
notifications: use the vendor-prefixed app info for display

[endlessm/eos-shell#2756]
notifications: force GTK_ICON_SIZE_DIALOG icon size

Force a pixel size too, so that we can work around applications not
shipping icons at all sizes.

[endlessm/eos-shell#2756]
search: use the vendor-prefixed app info for display

[endlessm/eos-shell#2756]
search: force GTK_ICON_SIZE_DIALOG icon size

Force a pizel size too, so that we can work around applications not
shipping icons at all sizes.

[endlessm/eos-shell#2756]
Merge pull request #8 from endlessm/shell/2756

Shell/2756
info: add link for license attribution

[endlessm/eos-shell#457]
Merge pull request #9 from endlessm/shell/457

info: add link for license attribution
Integrate with eos-license-service

[endlessm/eos-shell#457]
Allow Gnome control center to enable/disable metrics

Added Polkit rules, don't require an unlock for the control center.
[endlessm/eos-sdk#1327]
Merge pull request #11 from endlessm/sdk/1327

Allow Gnome control center to enable/disable metrics
rules: add "sudo" to the allowed groups for polkit rules
Fix typo in previous commit
privacy: wire the Metrics enabled switch to the daemon

[endlessm/eos-shell#2728]
Merge pull request #12 from endlessm/shell/2728

privacy: wire the Metrics enabled switch to the daemon