More readable timeline

[jrubenoff]

An assumption: when a vendor looks at an opportunity, they care about this information in order of priority:

1. When submissions are due (or, if the submission period hasn't started, when the period opens)
2. When questions are closed (or, if it's not yet open for questions, when it opens)
3. When it's posted, to confirm it's a fresh listing

The timeline should visually reflect these priorities. So, for example, if submissions and questions aren't yet open, the sidebar could look like this:

Once submissions and questions are open, users don't care when that happened. So the sidebar could change to this: