Add support for metainfo about plugin dependencies

@see http://wordpress.org/plugins/plugin-dependencies/
@see https://github.com/x-team/wp-plugin-dependencies
Darn.. let's get the tags from the correct file
Same for package
Whitespace
Capitalisation
Merge pull request #16 from jrfnl/Support-plugin-dependencies-metadata

Add support for metainfo about plugin dependencies