Share publications to corporations

[AquiGorka]

Ref: #27

This is the simplest form of "social sharing": links to urls prepared to post to the users feed (facebook) and post to the users timeline (twitter).

We can add open graph parameters to the head section which will append an image & tittle to facebook's sharer. We will probably add the pertinent information when this other issue is worked on, so I won't work on it in this PR.

[chadoh]

This works as a first pass. I see one problem with it, which we don't need to solve now:

Given the transient nature of how we're building the storage mechanism (no Filecoin or any easy way to let people secure their own data), the file will be picked up initially by Facebook/Twitter, but on later views if the data disappears from Thicket, then it won't show up on Facebook/Twitter, either.

I'm not sure if there's a way to get around that by uploading directly to Facebook/Twitter. Maybe we shouldn't even want to, but should instead prefer adding our own, more permanent data storage mechanism to Thicket.

[AquiGorka]

Ok. Let's do some brainstorming then on how we think sharing should work/behave and take it from there. I'll merge this so that we have some base.