The action and the views were almost identical, with the supports
progress and the HTML classes of the success message element being the
only exceptions; we can use CSS for the styles instead.
Just like we did in commit 0214184b2d for investments, we're removing
some possible optimizations (we don't have any benchmarks proving they
affect performance at all) in order to simplify the code.
The investement votes component `delegate` code was accidentally left
but isn't used since commit 0214184b2, so we're removing it now that
we're removing the `voted_for?` helper method.
