Review and Import PR's against BrowserMob Proxy

[ericbeland]

I'd like to grab some of the low-hanging PR fruit from the browsermob proxy, but only if they seem 1-fairly predictable, and 2-fairly well implemented. Please review these and bring them in if they seem solid.

Credentials leak fix:
https://github.com/lightbody/browsermob-proxy/pull/756/files

Brotli support:
lightbody/browsermob-proxy#783

Content Type Recognition:
lightbody/browsermob-proxy#731

[ericbeland]

I opened these items as PR's that we can evaluate individually. I'm closing this issue out.