gitignore: add ant target directory

Signed-off-by: Noah Watkins <noahwatkins@gmail.com>
Report librados error code in RadosException msg

Signed-off-by: Noah Watkins <noahwatkins@gmail.com>
Use librados default client name

Rados wants NULL for the default client name.

Signed-off-by: Noah Watkins <noahwatkins@gmail.com>