Fix paths - should be relative to work through reverse proxy

In public/js/all.js there were a number of absolute references to URLs, and one incorrect relative URL.

When including config.json the request is for '../config.json' but './config.json' resolves fine. Normally in the root directory this isn't a problem, but in the case of a reverse proxy (e.g. blah.com/coinpunk) coinpunk requests config.json from one directory too high.
Fix: remove the ../ from the path

In addition, references to the api included a leading slash (/api) which again, works on the root directory but not through a reverse proxy.
Likewise, the path to the listener was /listener - leading slash now removed.

Coinpunk now works through a reverse proxy and works just fine running it the way suggested in the readme - as far as I can tell.