Add privacy/security HTTP headers

[StuartMorrisAU]

Please consider adding privacy/security-related HTTP headers to *.*.usefathom.com, such as:

• HSTS, and add to Chrome preload list
• Content-Security-Policy
• CORS
• X-Frame-Options
• X-XSS-Protection
• X-Content-Type-Options
• Referrer-Policy
• Feature-Policy

www.usefathom.com returns a certificate error. Should this redirect to https://usefathom.com instead?

[JackEllis]

@StuartMorrisAU Thank you sir.