Fix #324

Added support for string hosts in ConnectionAbstract constructor.
Host constructor is used with supplied host string to create host object for ConnectionAbstract.

src/lib/connection.js

@@ -22,6 +22,8 @@ function ConnectionAbstract(host, config) {
     throw new TypeError('Missing host');
   } else if (host instanceof Host) {
     this.host = host;
+  } else if (typeof host === "string"){
+    this.host = new Host(host);
   } else {
     throw new TypeError('Invalid host');
   }
@@ -96,4 +98,4 @@ ConnectionAbstract.prototype.setStatus = function (status) {
   if (status === 'closed') {
     this.removeAllListeners();
   }
-};
+};