Implement unit testing

[ariamckinley]

Unit testing needs to be implemented at some point. These tests should be fairly extensive making sure that the components and utilities function as expected.

Some tests that need to be created:

• Make sure the Row component accepts the divisions prop
• Make sure the Row component applies the divisions prop to child Columns and Rows.
• Make sure the Row component only applies the divisions prop to children of type Column or Row.
• Make sure the Column component renders at width: (100% ÷ props.divisions) * sm
  • Repeat the above test for every media size.
• Make sure the Column component renders the margin-left in accordance with the xxShift prop.

I'm sure there will be more to list, but this is a solid start for now.