scikit-bio: scikit-bio 0.4.2: Maintenance release

We're very excited to announce scikit-bio 0.4.2. <strong>This is the last Python 2.7 compatible release. Future scikit-bio releases will only support Python 3.</strong> This is a maintenance release containing a number of bug fixes, as well as support for reading and writing Stockholm files. You can review the CHANGELOG.md for a complete description of the changes in this release. To learn about what you can do with scikit-bio, you should browse our (awesome!) API documentation. Be sure to follow @scikitbio on twitter for project updates, and as always, thanks for your interest in scikit-bio!