Log Message:
Update net/mitmproxy to 0.16.

Changes:
v0.16
-----
  * Completely revised HTTP2 implementation based on hyper-h2 (Thomas
    Kriechbaumer)
  * Export flows as cURL command, Python code or raw HTTP (Shadab Zafar)
  * Fixed compatibility with the Android Emulator (Will Coster)
  * Script Reloader: Inline scripts are reloaded automatically if modified
    (Matthew Shao)
  * Inline script hooks for TCP mode (Michael J. Bazzinotti)
  * Add default ciphers to support iOS9 App Transport Security (Jorge
    Villacorta)
  * Basic Authentication for mitmweb (Guillem Anguera)
  * Exempt connections from interception based on TLS Server Name Indication
    (David Weinstein)
  * Provide Python Wheels for faster installation
  * Numerous bugfixes and minor improvements