For the smallest breakpoint, expands the sidemenu to be width 100% and
to be toggled on or off rather than visible all the time.

* dashboard menu: fix overlap by singlestat and panel link icon

* refactor: navbar z-index

* hide grafana icon in solo panel mode

Added border radius and tightened up the folder boxes. Still needs to have the bottom margin expanded to 8px when in opened state (this needs @torkelo)