[#665] Currents component
[#665] Rename post_entry to js-post-entry

* consistency of _ vs -

* prepend js- to make it clear that we're using the id for convenience
  in locating the form in js
[#665] Comment and age restriction components
[#665] Remove extra padding-bottom

The last form element has a padding-bottom of 1rem; the fieldset has a
padding of 1.25rem. This creates a doubled-padding at the bottom of the
component, so let's make remove some padding from the fieldset.

Note: best would be to remove the bottom padding from the last form
element, but then we'd have to be aware of which HTML element was
visible. This is hackier, but ultimately seems simpler
[#665] Access component
[#665] Move custom access groups to a modal

* more space to spread out content, especially with showing who can see
  the entry
[#665] Remove extra bottom padding take 2

Previous solution led to an annoying jiggle on page load. Also, hacky!
So let's do it this way: use jQuery to detect the last visible row and
set the .last-visible class for a component that has extra elements that
are hidden/displayed by JS. If not, then the original CSS which uses
:last-child works just fine

(If there's no JS, we only have a little extra padding for specific
components -- not a dealbreaker)