Delete auxiliary module

Hi @inkrypto, this pull request tries to delete modules/auxiliary/server/emc_alphastor_75_cmd_injection.rb from the branch used on https://github.com/rapid7/metasploit-framework/pull/3686

I've converted the auxiliary module into an exploit here: https://github.com/rapid7/metasploit-framework/pull/3756 

Would be super useful if you could review and join  https://github.com/rapid7/metasploit-framework/pull/3756! Also feel free to get the changes on https://github.com/rapid7/metasploit-framework/pull/3756 and make them (or similar) by yourself. No problem on my side with deleting https://github.com/rapid7/metasploit-framework/pull/3756 if you prefer to work on it by yourself!

Thanks!