Update rubyzip version to a at least 1.0.0

The Zip::ZipFile class was changed to Zip::File, and the require directive was changed `require 'zip'`
I also fixed all the specs and added a constaint to rubyzip dependency.

Details are at https://github.com/rubyzip/rubyzip
Merge pull request #1 from yoavmatchulsky/update_rubyzip_version

Update rubyzip version to a at least 1.0.0 (thanks to yoavmatchulsky).