Navigation block does not have keyboard support

This patch can be tested as follows: Test that navigating with a keyboard is possible. Keys used in this test include : Tab, Space, Enter, Left Arrow (LA), Right Arrow (RA). 1) Tab through till the navigation block. Test that you can tab through every single branch node and leaf node. 2) Test that every non-link branch node toggle expansion on keys [Enter,Space] . 2a)Test [RA] only expands and [LA] only collapses the branch. 3) Test that every link node toggles expansion on a [space] keypress but follows the link upon an [enter] keypress. 3a)Test [RA] only expands and [LA] only collapses the branch. 4) repeat steps 1-3 on the settings block. 5) collapse the navigation and settings blocks into the dock. 6) Test that you can Tab through the dock items. 7) Tab to the 'remove all' button at the end of the dock. Test that Enter removes all blocks into the page and removes the dock. 8) repeat (5). 9) Tab to a docked block. 10) Test that docked blocks can be viewed with [RA] , a long single [RA] keypress shouldn't affect viewing. 11) Tab the the close panel icon in the block being viewed. Test that [Enter] hides the block into the dock again. 12) Test toggling viewing a docked block with [enter,space] keys. 13) Test collapsing the block with [LA] , a long single [LA] keypress shouldn't affect docked state. 14) (not part of patch test as it was already working for me but for fun) View a docked block. Tab to undock button within block. Test that you can undock a single block with [enter] .