Henrik Bengtsson's clean up of package and some effort to reduce memory footprint

Tagging this release, so it's cite-able as https://github.com/mskcc/facets/releases/tag/v0.6.1

Tagging this release, so it's cite-able as https://github.com/mskcc/facets/releases/tag/v0.6.0

Tagging this release, so it's cite-able as https://github.com/mskcc/facets/releases/tag/v0.5.14

This release generated as per lordzappo request (issue #23)

This is the release prior to implementing some major changes to the package.