Fixes #

This pull request:
- [ ] Has a title that summarises what is changing.
- [ ] Updates the documentation accordingly.
- [ ] Has unit tests & [code coverage](https://coveralls.io/github/sdss/marvin) is not adversely affected (within reason).
- [ ] Works with Python 2.7 and 3.6 (and ideally with Python 3.7).
- [ ] Updates the [CHANGELOG](https://github.com/sdss/marvin/blob/master/CHANGELOG.rst).
- [ ] Removes more lines of code than it adds.
- [ ] If relevant, adds a new entry to the `What's new?` page.

Fixes #

This pull request:
- [ ] Has a title that summarises what is changing.
- [ ] Updates the documentation accordingly.
- [ ] Has unit tests & [code coverage](https://coveralls.io/github/sdss/marvin) is not adversely affected (within reason).
- [ ] Works with Python 2.7 and 3.6 (and ideally with Python 3.7).
- [ ] Updates the [CHANGELOG](https://github.com/sdss/marvin/blob/master/CHANGELOG.rst).
- [ ] Removes more lines of code than it adds.
- [ ] If relevant, adds a new entry to the [What's new?](https://github.com/sdss/marvin/blob/master/docs/sphinx/whats-new.rst) page.

Add link to what's new in PR
Add link to what's new in PR
