Update gems.

Rspec was giving occasional "undefined `run_all' for []:Array" errors.
See: http://www.ruby-forum.com/topic/788351
Added #write to file system driver
Added #list_long and #list_short to file system driver
Fix example

Was busted by f3a37f4 (Added #list_long and #list_short to file system driver)
Add tests for the example