CLC-953 - When there is no content in My Classes, the message has no top padding

https://jira.media.berkeley.edu/jira/browse/CLC-953

Also fixes an issue where Due and Overdue aren't on the same height http://cl.ly/M55e
Merge pull request #465 from christianv/CLC-953

CLC-953 - When there is no content in My Classes, the message has no top padding