Add missing @since tags for new API

Change-Id: I900d745195f58c067fadf209bb92cd3c852c59f4
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

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

@@ -195,6 +195,7 @@ public class PersonIdent implements Serializable {
 	 * @param aName
 	 * @param aEmailAddress
 	 * @param when
+	 * @since 4.6
 	 */
 	public PersonIdent(String aName, String aEmailAddress,
 			ProposedTimestamp when) {

org.eclipse.jgit/src/org/eclipse/jgit/util/HttpSupport.java

@@ -144,7 +144,10 @@ public class HttpSupport {
 	/** The {@code gzip} encoding value for {@link #HDR_ACCEPT_ENCODING}. */
 	public static final String ENCODING_GZIP = "gzip"; //$NON-NLS-1$
 
-	/** The {@code x-gzip} encoding value for {@link #HDR_ACCEPT_ENCODING}. */
+	/**
+	 * The {@code x-gzip} encoding value for {@link #HDR_ACCEPT_ENCODING}.
+	 * @since 4.6
+	 */
 	public static final String ENCODING_X_GZIP = "x-gzip"; //$NON-NLS-1$
 
 	/** The standard {@code text/plain} MIME type. */