fix browserify bundle by not ignoring node-stringprep since it loads at least its fallbacks
fix browserify bundle by not ignoring node-stringprep since it loads at least its fallbacks

mweibel/node-xmpp-client,node-xmpp/node-xmpp,ggozad/node-xmpp,capablemonkey/node-xmpp-client,node-xmpp/node-xmpp,capablemonkey/node-xmpp-client,xmppjs/xmpp.js,ggozad/node-xmpp,xmppjs/xmpp.js