Updated ByteArrayLoader

Uses System.arraycopy instead of manually setting each value. Should be
faster.
Added ArrayDataAccessConverter

Added a specialized converter for populating ArrayImgs.

This required the following supporting changes:

* Converted the typed ArrayLoader implementations to expose their
  conversion methods, which can be leveraged by the
  ArrayDataAccessConverter.
* Updated the PlanarConverter API to take a Reader instead of a
  Metadata, to allow ArrayLoader instantiation.