Make selected status of Epic remembered

COS:

• Include in the URL
• In addition to the selected status of an issue

Discussion:
Selection states across tiered items: parent/child -
Mimic some common approaches like mail clients - folder can be selected, when child item is selected, folder has a "secondary selection" that shows it is still active, but not the active selection.

Bringing up details -
Thinking about this further in light of showing the Epic "details" on the right, I don't think we want to do this on Select of the Epic. That should be a primary action that is to filter the backlog list.

It may be worthwhile to add a "details" affordance though to manually display the issue details for an epic (just not on epic selection). I'll add that to the next iteration of the design.