Changes to CSV upload
- Fixed csv uploader to allow "Select None" option
- Wrote a test to make sure using the "Select None" option passes
Likes should be destroyed with a user.

Addresses #1175
Merge pull request #1180 from mmcguinn/scratch

CSV upload issues
Merge pull request #1181 from jdalphon/master

Changes to CSV upload
Merge pull request #1183 from jdalphon/jd_issue1175

Delete likes with users
-Changed hint for email to note that it will be required in the near future.