Resolve "Third party plugin sharing"

Tristan Maatrequested to merge
70-third-party-plugin-sharing into master

Closes #70 (closed)

Adds support for setuptools-based plugins that implement the buildstream.plugins entry point - see for example tristan/buildstream-plugins. Plugins can be enabled by specifying '<package>/<plugin>' as the 'kind' attriubte in a source or element.

Edited by Tristan Maat

Merge request reports