Fix lint issues from #22

[kandersolar]

• Closes #xxxx
• I am familiar with the contributing guidelines
• Tests added
• Updates entries in docs/sphinx/source/reference for API changes.
• Adds description and name entries in the appropriate "what's new" file in docs/sphinx/source/whatsnew for all changes. Includes link to the GitHub Issue with :issue:`num` or this Pull Request with :pull:`num`. Includes contributor name and/or GitHub username (link with :ghuser:`user`).
• New code is fully documented. Includes numpydoc compliant docstrings, examples, and comments where necessary.
• Pull request is nearly complete and ready for detailed review.
• Maintainer: Appropriate GitHub Labels (including remote-data) and Milestone are assigned to the Pull Request and linked Issue.

Fixes a few linter issues from #22:

./pvfactors/geometry/pvrow.py:8:1: F401 'shapely.geometry.GeometryCollection' imported but unused
./pvfactors/geometry/pvrow.py:844:5: F811 redefinition of unused 'boundary' from line 713
./pvfactors/viewfactors/vfmethods.py:243:45: E203 whitespace before ','
1     E203 whitespace before ','
1     F401 'shapely.geometry.GeometryCollection' imported but unused
1     F811 redefinition of unused 'boundary' from line 713
3

[kandersolar]

Changes are so basic that I will merge without review.