Fix uri prefix detection

foo,bar:baz is not a valid uri.

Refs: json-schema-org/JSON-Schema-Test-Suite#419

formats.js

@@ -13,7 +13,7 @@ exports['time'] = /^\d{2}:\d{2}:\d{2}$/
 exports['email'] = function (input) { return (input.indexOf('@') !== -1) && (!reEmailWhitespace.test(input)) }
 exports['ip-address'] = exports['ipv4'] = createIpValidator({ version: 4 })
 exports['ipv6'] = createIpValidator({ version: 6 })
-exports['uri'] = /^[a-zA-Z][a-zA-Z0-9+-.]*:[^\s]*$/
+exports['uri'] = /^[a-zA-Z][a-zA-Z0-9+\-.]*:[^\s]*$/
 exports['color'] = /(#?([0-9A-Fa-f]{3,6})\b)|(aqua)|(black)|(blue)|(fuchsia)|(gray)|(green)|(lime)|(maroon)|(navy)|(olive)|(orange)|(purple)|(red)|(silver)|(teal)|(white)|(yellow)|(rgb\(\s*\b([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])\b\s*,\s*\b([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])\b\s*,\s*\b([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])\b\s*\))|(rgb\(\s*(\d?\d%|100%)+\s*,\s*(\d?\d%|100%)+\s*,\s*(\d?\d%|100%)+\s*\))/
 exports['hostname'] = function (input) {
   if (!(reHostnameFirstPass.test(input))) return false