Replace the front page image and add a laptop_frame image.
Remove the workshop folder and point all workshop references to docs.geonode.org.

* Set the workshop paths to context variables in plugins/geonode.py.
* Delete the workshops/ dir.
Change the demo site url to demo.geonode.org.
Delete the workshops directory.
Merge pull request #15 from garnertb/website_improvements

Website improvements.