5.1.4 (May 14, 2019)

• Migrate from requestjs to axios (thanks to @FX-Wood)
• Enable page templates to add items to the HTML head element
• Fix bold font issue on macs (thanks to @neighlyd)
• Use BASE_URL for github
• Update min node engine to require Feb 2019 NodeJS security release
• Add Node.js 12 to the travis build
• Update dependencies
• Update documentation (thanks in part to @anubhavsrivastava, @Fullchee, @luckymurari)