Fix up the Gantt charts

@suppermancool - We need to fix up the Gantt charts a bit:

Issue 1

The chart on the new challenge page is rendering differently than the edit challenge page. Ideally, these would be the same:

New challenge

Edit challenge

Issue 2

In terms of the phase duration, I got this clarification, so we can got with this assumption:

go now with the assumption that phase duration is hours

Final Submission Guidelines

Git issue link: https://github.com/topcoder-platform/challenge-engine-ui/issues/175