server configuration class. defined user list entry at configuration file for multi-user account.
fixed whitespace
unique-user-id command is defined.

maintenance tool. this command shows a hex ID from a username.
username is identified through hex ID in RIMS server.
server configuration class. base_dir attribute is changed to public for access from command utility.
show-user-mbox command is defined.

maintenance tool. this command shows the path in which mailbox data is stored.
changelog: * lib/rims/cmd.rb, lib/rims/server.rb: user list entry for multi-user account is defined at server configuration file. some maintenance commands of multi-user mailbox is defined.
Merge branch 'multiuser'
I/O string debug log utility function.
changelog: * lib/rims/protocol.rb: I/O string debug log utility function.
stop server message.
changelog: * lib/rims/server.rb: stop server message.