Create HTML-formatted contributor stats on the Bitcoin github repo. Based on bitcoin-core-stats but using a different data source and pared down features.

• Clone the github-metadata-backup-bitcoin-bitcoin, pull the latest master, and set the GH_META_DIR parameter in contributor-stats.py.
• Set the user (GitHub handle) and year (year to filter data) variables in contributor-stats.py
• Run contributor-stats.py > your-output-file.html to generate the HTML summary report.