Fauxton: use .listenTo and not .on

There was no `.off` call on destroy, so these two Eventhandlers
where leaking memory
Fauxton: Extract a common filter component from logs

Create a reusable component from the filter that is used in logs,
that can be used in for tasks like
COUCHDB-2158 ("Apply filter with custom params on changes feed page")
and other situtations where a filter is needed.
Fauxton: Cleanup whitespace
Fauxton: fix burger

- Fix z-index issue for Firefox, the burger doesn't need an own
  width and high z-index

- Fix accidental horizontal scrollbar in resize-handler

COUCHDB-2234
Remove unused transitions

They don't work any more since some time
Do not show version on a collapsed view
Readd z-index, fix height & width of burger

I think the initial intention was that the burger should be
visible and the content scrolls under it
Fauxton: Fix scrollbar from sidebar on collapsed state

With a collapsed sidebar, in Chrome, the scrollbar was always
visible, even if the z-index of the dashboard was higher.