Add toByteArray to CommitBuilder, TreeBuilder

This better matches the existing API of TreeFormatter, but is just a
simple delegation to build().

Change-Id: I188f43acc34455e773d63836724b05e18f5c7a84
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Reviewed-by: Chris Aniszczyk <caniszczyk@gmail.com>

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

@@ -310,6 +310,19 @@ public class CommitBuilder {
 		return os.toByteArray();
 	}
 
+	/**
+	 * Format this builder's state as a commit object.
+	 *
+	 * @return this object in the canonical commit format, suitable for storage
+	 *         in a repository.
+	 * @throws UnsupportedEncodingException
+	 *             the encoding specified by {@link #getEncoding()} is not
+	 *             supported by this Java runtime.
+	 */
+	public byte[] toByteArray() throws UnsupportedEncodingException {
+		return build();
+	}
+
 	@Override
 	public String toString() {
 		StringBuilder r = new StringBuilder();

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

@@ -193,6 +193,16 @@ public class TagBuilder {
 		return os.toByteArray();
 	}
 
+	/**
+	 * Format this builder's state as an annotated tag object.
+	 *
+	 * @return this object in the canonical annotated tag format, suitable for
+	 *         storage in a repository.
+	 */
+	public byte[] toByteArray() {
+		return build();
+	}
+
 	@Override
 	public String toString() {
 		StringBuilder r = new StringBuilder();