Updated grunt tasks for codegen.
Updated grunt tasks for codegen.

Always use the latest version of generator or spec packages in packages
directory instead of the first one found.

Removed obsolete target.

vivsriaus/azure-sdk-for-node,lmazuel/azure-sdk-for-node,Azure/azure-sdk-for-node,begoldsm/azure-sdk-for-node,huangpf/azure-sdk-for-node,devigned/azure-sdk-for-node,namratab/azure-sdk-for-node,smithab/azure-sdk-for-node,IoTboy/azure-sdk-for-node,mauricionr/azure-sdk-for-node,oaastest/azure-sdk-for-node,koistya/azure-sdk-for-node,mauricionr/azure-sdk-for-node,AutorestCI/azure-sdk-for-node,iwate/azure-sdk-for-node,msfcolombo/azure-sdk-for-node,kagamsft/azure-sdk-for-node,kagamsft/azure-sdk-for-node,xingwu1/azure-sdk-for-node,DeepakRajendranMsft/azure-sdk-for-node,begoldsm/azure-sdk-for-node,shrishrirang/azure-sdk-for-node,shrishrirang/azure-sdk-for-node,msfcolombo/azure-sdk-for-node,xingwu1/azure-sdk-for-node,mauricionr/azure-sdk-for-node,oaastest/azure-sdk-for-node,smithab/azure-sdk-for-node,msfcolombo/azure-sdk-for-node,namratab/azure-sdk-for-node,Matt-Westphal/azure-sdk-for-node,Azure/azure-sdk-for-node,koistya/azure-sdk-for-node,vivsriaus/azure-sdk-for-node,Azure/azure-sdk-for-node,xingwu1/azure-sdk-for-node,harshiam-hdinsight/azure-sdk-for-node,devigned/azure-sdk-for-node,Matt-Westphal/azure-sdk-for-node,DeepakRajendranMsft/azure-sdk-for-node,hveiras/azure-sdk-for-node,Matt-Westphal/azure-sdk-for-node,lmazuel/azure-sdk-for-node,harshiam-hdinsight/azure-sdk-for-node,IoTboy/azure-sdk-for-node,AutorestCI/azure-sdk-for-node,IoTboy/azure-sdk-for-node,shrishrirang/azure-sdk-for-node,AuxMon/azure-sdk-for-node,amarzavery/azure-sdk-for-node,amarzavery/azure-sdk-for-node,oaastest/azure-sdk-for-node,koistya/azure-sdk-for-node,AuxMon/azure-sdk-for-node,namratab/azure-sdk-for-node,devigned/azure-sdk-for-node,hveiras/azure-sdk-for-node,iwate/azure-sdk-for-node,huangpf/azure-sdk-for-node,iwate/azure-sdk-for-node,huangpf/azure-sdk-for-node