Partial-hour donations of time are disappearing

[mkimberlin]

Describe the bug
If you register that you participated in a volunteer event for 0.5 hours, that time is truncated and it shows as 0 hours after save.

To Reproduce
Steps to reproduce the behavior:

1. Go to your profile by clicking on your avatar on the upper right
2. Scroll down to 'Volunteer Orgs' and 'Events'
3. Click the 'Events' tab
4. Click the + icon
5. Enter information about an event (including selecting an organization)
6. For "Hours You Volunteered", enter 0.5
7. Save the event
8. Note that the table shows 0 hours
9. Click the edit (pencil) button for the event
10. Note that the time in the dialog says 0

Expected behavior
Partial hours should not be lost.

Screenshots