tooltips - removed duplicate/incorrect tooltip_manager.js reference in base.html and added tooltips to unit actions

optimize slightly, allow caller to pass in the list of units in a subsection, so we don't have to refetch

update creating a new unit to use an empty template. Also twiddle the units.html and base.js where we put the unit Location on the <li> element

add subsection edit page to the project with a shared 'unit' widget that will render out unit lists. Both edit_subsection and overview.html will share this widget