Change to use rubyzip 1.1.0 or newer

`jpi build` command fails like following:
```
$ jpi build
LoadError: no such file to load -- zip/zip
         require at org/jruby/RubyKernel.java:1084
         require at /Users/eito/Library/Homebrew/Cellar/rbenv/0.4.0/versions/jruby-1.7.8/lib/ruby/shared/rubygems/core_ext/kernel_require.rb:55
         require at /Users/eito/Library/Homebrew/Cellar/rbenv/0.4.0/versions/jruby-1.7.8/lib/ruby/shared/rubygems/core_ext/kernel_require.rb:53
          (root) at /Users/eito/Library/Homebrew/opt/rbenv/versions/jruby-1.7.8/gemsets/rvm-plugin/gems/jpi-0.3.8/lib/jenkins/plugin/tools/package.rb:3
         require at org/jruby/RubyKernel.java:1084
```

This is because jpi picks up the latest rubyzip gem (1.1.0 at this moment) and the gem has changed several things.

This PR should fix this issue to cope with those changes in rubyzip gem.