Update existing WebClip...

[angelo-v]

...instead of creating duplicate one for already bookmarked pages

As someone who already used WebClip for a while when opening WebClip on a page I already clipped in the past, I want to see the existing link to the clip so that I do not clip the same page over and over again

Acceptence critiera

• [x] WebClip shows the "Show in Pod" link when opened, if the page has already been clipped
• [x] I still can clip the page (again), but it will update my existing data on that clip, not create a new one

[angelo-v]

First acceptance criteria is fullfilled in #11 Second one needs to be done yet