Fix #1114 HttpUtils getGitblitURL does not support nonstandard ports

X-Forwarded-Host can contain port number and it is added twice in that situation
This fix just prevent adding port number if it is already there
diff --git a/src/main/java/com/gitblit/utils/HttpUtils.java b/src/main/java/com/gitblit/utils/HttpUtils.java
index 2fd8d89..27df5a5 100644
--- a/src/main/java/com/gitblit/utils/HttpUtils.java
+++ b/src/main/java/com/gitblit/utils/HttpUtils.java
@@ -110,7 +110,9 @@
 		sb.append(host);

 		if (("http".equals(scheme) && port != 80)

 				|| ("https".equals(scheme) && port != 443)) {

-			sb.append(":").append(port);

+			if (!host.endsWith(":" + port)) {

+				sb.append(":").append(port);

+			}

 		}

 		sb.append(context);

 		return sb.toString();