BytesLocation: add ctor with initial capacity

This makes it easier to create BytesHandles on the fly:

    bytes = dataHandleService.create(new BytesLocation(512));

instead of:

    bytes = dataHandleService.create(
      new BytesLocation(ByteBuffer.allocate(512)));

Author: gab1one

src/main/java/org/scijava/io/BytesLocation.java

@@ -60,6 +60,14 @@ public BytesLocation(final byte[] bytes, final int offset, final int length) {
 		this(ByteBuffer.wrap(bytes, offset, length));
 	}
 
+	/**
+	 * Creates a {@link BytesLocation} backed by a {@link ByteBuffer} with the
+	 * specified initial capacity.
+	 */
+	public BytesLocation(final int initialCapacity) {
+		this(ByteBuffer.allocate(initialCapacity));
+	}
+
 	// -- BytesLocation methods --
 
 	/** Gets the associated {@link ByteBuffer}. */