Rehomed command-classes so that Clamp would work correctly

NOTE: 'autoload_subcommands wants to be in only one place -
leave in last-loaded subcommand (in this case, users.rb)

$ env RUBYOPT=-Ilib hammer csv
Usage:
    hammer csv [OPTIONS] SUBCOMMAND [ARG] ...

Parameters:
    SUBCOMMAND                    subcommand
    [ARG] ...                     subcommand arguments

Subcommands:
    activation-keys               import or export activation keys
    architectures                 import or export architectures
    content-views                 import or export content-views
    domains                       import or export domains
    hosts                         import or export hosts
    lifecycle-environment         import or export lifecycle environments
    locations                     import or export locations
    operating-systems             import or export operating systems
    organizations                 import or export organizations
    partition-tables              import or export partition tables
    permissions                   import or export permissions
    products                      import or export products
    puppet-environments           import or export puppet environments
    puppet-facts                  import or export puppet facts
    puppet-reports                import or export puppet reports
    reports                       import or export reports
    roles                         import or export roles
    subscriptions                 import or export subscriptions
    system-groups                 import or export system groups
    systems                       import or export systems
    users                         import or export users

Options:
    -h, --help                    print help