Add summary data

Add a summary data "ribbon" to the landing page of the website to indicate activity. This is accomplished with the following:

• A scripts/summary_data.py Python script that fetches project and activity data from GitLab and XonStat APIs, respectively. It renders to the file provided as its first argument. It is designed to render all zero-values for all fields if any errors occur.
• A data/summary/summarystats.json file that houses the data fetched from the above step. Note: this location is important for visibility in templates!
• Template modifications to the index.html page for showing the ribbon if there is any data in the file. If no data is found (# of games is 0), the ribbon is not rendered at all.
• A phony Makefile target to make automating the website update/deploy actions super easy.

Please have a look, @martin-t, @DefaultUser, and @detrate.