Time descriptions with only numbers break OAR after saving the page

[crittermike]

1. Enter a time entry with a number as the only text in the description, such as "1234"
2. Save the timesheet
3. After the page reloads, the timesheet doesn't load, and you also can't switch to the original time grid to remove that entry

Looks like when parsing the timesheet to populate the OAR listing, we need to cast to string.