Add project statistics and convert to sortable table

This commit changes the previous alternative internet project index into a sortable table with project statistics sourced from ohloh.net.

To achieve this, every project currently in the README.md was converted to a JSON file, found in projects/. Pull requests for new projects should be done by adding a new JSON file in the projects/ folder and using the included update.py to regenerate the README.md files.

For more info, see the included CONTRIBUTING.md.