Hotfix: swagger send notification

• Source should be optional.
• Source value should be
  • email if == notification.source = email
  • web if == notification.source = web
  • by default apikey
• Default example notification should be pushed against channel 7ef95970-9fcb-413a-8f22-5c5e4aab713c
• Remove from default example: sendat, all targets, intersection, source

So in the end we get

{
  "body": "<p>My body</p>",
  "summary": "My notification",
  "target": "7ef95970-9fcb-413a-8f22-5c5e4aab713c",
  "priority": "NORMAL",
  "link": "https://notifications.web.cern.ch/",
  "imgUrl": "https://home.cern/sites/default/files/logo/cern-logo.png"
}