servers.json: Added "fulcrum.fountainhead.cash"
servers.json: Added "fulcrum.fountainhead.cash"

This server is run by Jt, who collaborates with James Cramer on SLP.  He
said he's committed to running a server now, so we updated the
servers.json file so he can get some users. :)

fyookball/electrum,fyookball/electrum,fyookball/electrum