Hammer CLI

When user has insufficient permissions for some action and the foreman replies 403, hammer prints quite a poor message without telling the user what permissions are required (even though server provides such info).

# With user without "View hosts" permissions:
> hammer -u test host list
Forbidden - server refused to process the request

The response from the server:

[ERROR 2017-06-27T11:15:48 API] 403 Forbidden
[DEBUG 2017-06-27T11:15:48 API] {
    "error" => {
        "message" => "Access denied",
        "details" => "Missing one of the required permissions: view_hosts" 
    }
}
[DEBUG 2017-06-27T11:15:48 Exception] Using exception handler HammerCLIForeman::ExceptionHandler#handle_forbidden
[ERROR 2017-06-27T11:15:48 Exception] Forbidden - server refused to process the request

Expected results:

> hammer -u test host list
Access denied
Missing one of the required permissions: view_hosts