Adds functionality to test for date fields with a start and end date

[patrickfweston]

This pull request accompanies the following issue: #11

This pull request fixes the issue by checking the value returned by the date field function to see if it is an array. If it is an array, both the start and end date are checked to match the value.

[becw]

This branch and PR need to be based off of master, since experimental won't be merged back in there--it's just a placeholder for the other open branches.

[patrickfweston]

@becw : Since my codebase in the project I made this fix for is based off of experimental, should I checkout master for the project and then make the changes? Otherwise, it will be akin to merging in experimental when this PR is merged.

[becw]

Yes, you should cut a fresh new branch off of master. You should be able to do:

git checkout master
git checkout -b some-new-branch
git cherry-pick fccca32^..56c907c