Updated version requirements for the Gem dependencies.
Added the required_ruby_version parameter to the Gem.
Added metadata to the Gem.
Ignoring the gem dependency graph png.
Removed the redundant 'test' group for bundler.
Removed the metadata attribute from gemspec.
Added back the test group in the Gemfile.
Merge branch 'next' into develop
Merge branch 'master' into develop

 explain why this merge is necessary,
Merge branch 'br0.9.0' into develop
Merge branch 'next' into develop
Merge branch 'next' into develop
adding a max_depth to the tree printing
Merge pull request #27 from Karamorf/develop

adding a max_depth to the tree printing
Applied the logic for the maximum depth specification for printing trees.
Applied the logic for the maximum depth specification for printing trees.
Merge branch 'next'.