Provide HTML and JSON HTTP handlers

[mreithub]

Add predefined GoRef methods to serve HTML and/or JSON output.

For the JSON output we can use the gorefJSON() method from the examples pretty much as-is.

For the HTML output I'm thinking of a table listing each entry and its fields (and maybe a little javascript for sorting/filtering/etc.)
The HTML output could also filter out null-entries (which can happen after a Reset())

(And all of that without adding any new dependencies)