Issue #171

server limit the number of webUI clients that can attach.

This will probably always be "0" or "unlimited", but allows ops to set a max limit for WebUI clients. (realistically, probably 3 is more than enough)

@crankycoder r?
Forgive my rampant and unchecked stupidity, but why is it `ws_proto` and `ws_hostname` (avec underscores), but then `ws.max_clients` (with a period)?

Should we change to `ws_max_clients` or switch everything to be `ws.*` (to be more consistent w/ `aws`, `heka`, and `db` objects elsewhere in this config.ini)?