Refactoring HostResolver.resolve, installation of PyYAML, removing flake8, added authors section to README

* refactoring HostResolver: in hostRpmBuilder there was a check if the result of HostResolver.resolve is empty ... since I did not find any other usage of .resolve I decided to move this into the function itself.
* Installing PyYAML via yum
* Removing flake8
* Created authors section in README