Implement Serializable interface in PersonIdent class.

Change-Id: I3229f4ec85e7604cb45642813757975b30f1227e
Signed-off-by: Kevin Sawicki <kevin@github.com>

org.eclipse.jgit/src/org/eclipse/jgit/lib/PersonIdent.java

@@ -45,6 +45,7 @@
 
 package org.eclipse.jgit.lib;
 
+import java.io.Serializable;
 import java.text.SimpleDateFormat;
 import java.util.Date;
 import java.util.Locale;
@@ -58,7 +59,9 @@ import org.eclipse.jgit.util.SystemReader;
  * Git combines Name + email + time + time zone to specify who wrote or
  * committed something.
  */
-public class PersonIdent {
+public class PersonIdent implements Serializable {
+	private static final long serialVersionUID = 1L;
+
 	private final String name;
 
 	private final String emailAddress;