Add support for notifications of new server or plugins updates

Description

. Let admins receive notifications of new updates (server or plugins)
. Let admins disable the check for update service
. Let admins disable the notification of new updates
. Change the main page of the admin console to alert admins when a new release is available
. Change the plugins page to show when a new version is available
. Add a new page to show available plugins to download and install

By default check for updates every 48 hours. Let admins change the frequency.

Environment

None
Fixed

Assignee

Gaston Dombiak

Reporter

Gaston Dombiak