Refactoring datastore package

Preparation to make datastore replacable
- Extract datastore interfaces
- Add multi Read/Write/Remove
- Add a method to walk over RCTable
- Refactor serialize/deserialize RCObject
- Localize dependency to JRAMCloud
  - Separate RAMCloud specific code into ramcloud package
  - Remove dependency to RAMCloud exception classes
  - Remove RC prefix from non RAMCloud specific code
- Cosmetics and update sample/test code

- reflect Naoki's comment
- more cosmetic fixes
  - reordered OPERATION enums

- removed no longer used code
- follow pmd, etc. where easily possible

Change-Id: I6f9153d705600447acf48a64f713c654c9f26713
diff --git a/src/main/java/net/onrc/onos/datastore/utils/ByteArrayUtil.java b/src/main/java/net/onrc/onos/datastore/utils/ByteArrayUtil.java
index 96f8743..c13d7ea 100644
--- a/src/main/java/net/onrc/onos/datastore/utils/ByteArrayUtil.java
+++ b/src/main/java/net/onrc/onos/datastore/utils/ByteArrayUtil.java
@@ -4,13 +4,35 @@
 
 public class ByteArrayUtil {
 
+    // Suppresses default constructor, ensuring non-instantiability.
+    private ByteArrayUtil() {}
+
+    /**
+     * Returns a StringBuffer with each byte in {@code bytes}
+     * converted to a String with {@link Integer#toHexString(int)},
+     * separated by {@code sep}.
+     *
+     * @param bytes byte array to convert
+     * @param sep separator between each bytes
+     * @return {@code bytes} converted to a StringBuffer
+     */
     public static StringBuffer toHexStringBuffer(final byte[] bytes,
 	    final String sep) {
 	return toHexStringBuffer(bytes, sep, new StringBuffer());
     }
 
+    /**
+     * Returns a StringBuffer with each byte in {@code bytes}
+     * converted to a String with {@link Integer#toHexString(int)},
+     * separated by {@code sep}.
+     *
+     * @param bytes byte array to convert
+     * @param sep separator between each bytes
+     * @param buf StringBuffer to append to.
+     * @return {@code buf}
+     */
     public static StringBuffer toHexStringBuffer(final byte[] bytes,
-	    final String sep, StringBuffer buf) {
+	    final String sep, final StringBuffer buf) {
 	if (bytes == null) {
 	    return buf;
 	}