Adding some comments to the new code in FTPSERVER-302

git-svn-id: https://svn.apache.org/repos/asf/mina/ftpserver/trunk@782450 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/core/src/main/java/org/apache/ftpserver/impl/PassivePorts.java b/core/src/main/java/org/apache/ftpserver/impl/PassivePorts.java
index 2750c0e..338c4ba 100644
--- a/core/src/main/java/org/apache/ftpserver/impl/PassivePorts.java
+++ b/core/src/main/java/org/apache/ftpserver/impl/PassivePorts.java
@@ -166,6 +166,9 @@
         this.checkIfBound = checkIfBound;
     }
 
+    /**
+     * Checks that the port of not bound by another application
+     */
     private boolean checkPortUnbound(int port) {
         // is this check disabled?
         if(!checkIfBound) {
@@ -183,7 +186,7 @@
             ss.setReuseAddress(true);
             return true;
         } catch (IOException e) {
-            // port probably in used, check next
+            // port probably in use, check next
             return false;
         } finally {
             if(ss != null) {