Implement local report endpoint

[MrLuit]

• Implements config.apiKeys.Google_Captcha and config.apiKeys.Slack_Webhook
• When a Google Captcha secret is not found, the app will not verify incoming the captcha responses
• If no Slack webhook is provided, all reports will be sent to the cryptoscamdb.org endpoint

Previously all reports were sent to a PHP server I run, but obviously that's not really secure

[blurpesec]

Stuck pending submission:

report.js:7 Uncaught ReferenceError: reportEndpoint is not defined
    at HTMLDivElement.<anonymous> (report.js:7)
    at HTMLDivElement.d.complete (jquery.min.js:3)
    at i (jquery.min.js:2)
    at Object.fireWith [as resolveWith] (jquery.min.js:2)
    at i (jquery.min.js:3)
    at Function.r.fx.tick (jquery.min.js:3)
    at eb (jquery.min.js:3)

I get stuck on the step after gcaptcha here: