Sort stories, show status & date in selection UI, and add some more keybindings to selection UI

Bugfixes:

• fixed an issue (sometimes) getting the Pivotal API key from git-config by trimming space from the resulting string

New features:

• stories are now sorted most-recently-updated first (refresh your stories to see the effect)
• in the selection UI:
  • story status is now displayed
  • story last-updated timestamp is now displayed
  • added keybindings:
    • G for jump to end
    • g for jump to top
    • n for next
    • p for previous

Upgrade Notes:

There might be a problem when it tries to load your cached stories file made by the previous version. Either delete the cached file (~/.gg-git-hooks-cache.json) or preemptively run:

goodguide-git-hooks update-pivotal-stories