Ruby mogilefs-client 3.4.0

Admin speedups for get_domains, get_hosts, and get_devices.
Previous versions were completely unusable for parsing a list of
3000+ domains.  Installations with thousands of hosts or devices
should see noticeable performance improvements.

The client interface gains the each_file_info iterator method.
This behaves like each_key, but gives access to the entire
response the file_info returns, including: checksum, devcount,
file size, class, and domain.