Merge pull request #1 from mvz/issue-work-with-current-ruby-graphviz

Make DepGraph work with current ruby-graphviz
Bump to 0.11.0
Update master
Parses Chef cookbook metadata/directory for dependencies.
Taking out those puts'es.
Modifications to graph_creator to support multiple formats.
Add support for the -json flag (+ JSON depgraph generation)
Model dependency on rake-compiler gem.
Getting rid of all those putses.