Add a way to share datasets and see mentions of datasets on twitter (and elsewhere)

[rgrp]

As a visitor I want to share a link to a dataset I have found. I also want to see how many others have shared this (or mentioned it).

• Sharing platform: simplest option is probably twitter but could generalize to e.g. sharethis system which supports, facebook, twitter etc etc.
  • Will need a config option for relevant API key e.g. ckan.sharethis.apikey
• Location: Put this at top of sidebar on dataset view (a better suggsetion?)
• Should show how many mentions / shares there are. (very important!)

Discussion

• (Tom and Ira and ...): do we really want this, versus e.g. proper follow extension?
• What about bringing conversation back in to CKAN. E.g. show all times this dataset (i.e. its url) was mentioned on twitter. If we do this I think this should be definite +1.
• Also, given our users, I think just doing twitter (identica) may be sufficient (how many people want to share links to datasets on facebook?)