Dispatcher module for command line interface programs
'App::CLI' dispatches CLI (command line interface) based commands into
command classes. It also supports subcommand and per-command options.
give options map, process by Getopt::Long::Parser
interface of dispatcher
find package name of subcommand in constant %alias
if it's finded, return ucfirst of the package name,
otherwise, return ucfirst of $cmd itself.
return subcommand of first level via $ARGV