CLC-966 - Provisional task adding
https://jira.media.berkeley.edu/jira/browse/CLC-966

This is a follow up on #473

Fixes the following:

* You can't submit the same task twice
* Adding a task with a date now works
* Removing duplicate code
* Simplify the splitting of dates code
* Whitespace issues
Merge pull request #483 from christianv/CLC-966

CLC-966 - Provisional task adding