v0.2.0t adds favicon, navbar, and jwt auth support

Adds the following config.json options beyond those already in v0.2.0s:

• favicon_url
• top_html
• jwt_login_url
• jwt_cookie_name
• jwt_secret_key

The first two adds a favicon and minimal top navigation bar.

The remaining jwt_* items permit adding authenticated access as a reverse proxy.

v0.2.0s adds TLS support to v0.2.0

CHANGELOG

• Add config.json options ""full_cert_filename" and "priv_cert_filename" which enable TLS.
  "full_cert_filename" is the full certificate chain (in .pem or other format accepted by Go runtime)
  "priv_cert_filename" is the private key for the certificate

• Add config.json options "jwt_login_url", "jwt_cookie_name", "jwt_secret_key" for auth using JWT.
  "jwt_login_url" is the redirect login url if JWT is missing or invalid
  "jwt_cookie_name" is the name of the cookie where the JWT is expected
  "jwt_secret_key" is the base64 (standard RFC 4648) of the HS256 secret

• Add config.json option "proxy_path_urls" which is a map of string to string with paths for keys (e.g. "/login") and urls for values (e.g. "https://my-login-server.com/login")

The *cert* and jwt* parameters should be used with the --addr :443 command-line option (unless an encrypting proxy is used).

Rebuild of v0.2.0 using go1.11.2

Merge pull request #298 from etsy/health-check-002

Added health-check-uri to example config.