Add associations to hosttag spec
Add associations to hosttag spec

Mdm::HostTag spec didn't test associations
Added appropriate specs
not much to see here

rapid7/metasploit-cache,bcook-r7/metasploit_data_models,rapid7/metasploit-model,rapid7/metasploit-cache,rapid7/metasploit-cache,bcook-r7/metasploit_data_models,rapid7/metasploit_data_models,farias-r7/metasploit_data_models,rapid7/metasploit-cache,rapid7/metasploit-model,rapid7/metasploit_data_models,bcook-r7/metasploit_data_models,rapid7/metasploit-model,farias-r7/metasploit_data_models,farias-r7/metasploit_data_models,rapid7/metasploit_data_models