Upgrade to CKAN 2.0

Right now, we only add the disqus comments in package/read.html.
Update gitignore
Tidy up (convert tabs to spaces)
Add home image
Replace 'what are groups' with new 'about groups' text.
Replace 'what are datasets' with new 'about datasets' text.
new styling added
Make case of home page titles consistent
link colour
Merge branch 'release-v2.0' of https://github.com/okfn/ckanext-datahub into release-v2.0
Add footer template (change okfn.org link to okfn.org/services)
Show 'Add Dataset' button even when not logged in
Change URL for 'Register data' button to /dataset/new
Add "popular Tags", increase tag font size.
Update home page text
Add footer opendata image to extension (instead of fetching from okfn.org)
Add recaptcha to user registration form
Add wrapper div around disqus comment block to fix styling
Remove upload button from new_resource template
Add paster 'spammer' command to kill a user and all of the datasets that they created.
Add find-spam paster command