Fixes #5613 - Fix unhandled sys errors BZ1084722

In hammer-cli-katello's system subcommand, when system-id given is
invalid, only a Bad Request message is presented to the user. This is
because the error messages being returned when a system is not found are
not being rendered using app/lib/katello/api/v2/error_handling.rb.

* Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1084722
Merge pull request #4059 from dustint-rh/bz1084722_hammer_queries_for_missing_system_id

Fixes #5613 Fixes problem with hammer only returning Bad Access when sys...