enable a config flag to disable librarian-chef if needed
fix indent, add missing period, extract main call to a private method
plugin is enabled by default when config flag is not set
Merge pull request #24 from looztra/option_enabled

enable a config flag to disable vagrant-librarian-chef if needed
Improve yard docs and code formatting.
Document new "enabled" config attribute.
Bump version to 0.2.0.