Vulnerability Report enhancement

- update `#report_service` and `#report_vuln`
- update vulnerability report when a session is established
- update CheckCode and `#cmd_check` to report a vulnerability when
  Vulnerable checkcode is returned
- update `vulns` and `services` commands to display the `resource` and
  parent services
- specs

spec/api/json_rpc_spec.rb

@@ -225,6 +225,7 @@ RSpec.describe "Metasploit's json-rpc" do
             result: {
               code: 'safe',
               details: {},
+              vuln: {},
               message: 'The target is not exploitable.',
               reason: nil
             }