Force default encoding to UTF-8 on newer ruby releases

This is to avoid issues with UTF-8 characters in input files (as happening on
e.g. SLE12). See https://tickets.opscode.com/browse/CHEF-3304.
Merge pull request #356 from rhafer/encoding-sle12

Force default encoding to UTF-8 on newer ruby releases
Fixed permissions
Replaced constants with env vars
Fixed raw/custom proposal links
Cleaned crowbar config and added travis image to readme

The goal is to remove the package requirements from the crowbar
configuration as the dev tool and all the dependencies for building isos
on the dell way is not maintained anymore and move the packaging to obs
instead.
Added ruby 2.1.0 to travis config