Attributes/service name

This PR add support for a different service name than the package name, cause your package can be [named](https://github.com/viverae-cookbooks/apache2/blob/master/attributes/default.rb#L73) after mycompany-httpd then the cookbook will fail to find the init script for the service. This PR fix that.
If you merge #288 you can merge this with out problems,or  just merge this (if you ok with both changes of course) and close the other.