provider_skeleton Exploit Clean and Fixes

Hi @matthiaskaiser,

This pull request tries to fix https://github.com/rapid7/metasploit-framework/pull/2011, applying fixes proposed by @limhoff-r7 and @jlee-r7. Also tries to make claen up, add references, makefile, delete the old click2play bypass and modify ranking according to the exploit capabilities.

Please feel free to review, test, discuss anything and land into your repository once you agree with changes. In this way the original pull request https://github.com/rapid7/metasploit-framework/pull/2011 will be automatically updated and ready to be landed I guess!

Thanks for your collaboration!