Make Capybara check the page between custom votes

As pointed out in PR consul#2734:

"After clicking the first link, there's an AJAX request which replaces
the existing `.in-favor a` and `.against a` links with new elements. So
if Capybara tries to click the existing `.against a` link at the same
moment it's being replaced, clicking the link won't generate a new
request".

Making Capybara check the page for new content before clicking the
second link solves the problem.

This commit solves issues affecting Madrid's fork but not the original
CONSUL repo.

spec/features/comments/spending_proposals_spec.rb

@@ -460,6 +460,11 @@
 
  within("#comment_#{@comment.id}_votes") do
  find('.in_favor a').click
+
+ within('.in_favor') do
+ expect(page).to have_content "1"
+ end
+
  find('.against a').click
 
  within('.in_favor') do

spec/features/custom/probe_option_comments_spec.rb

@@ -468,6 +468,11 @@
 
  within("#comment_#{@comment.id}_votes") do
  find('.in_favor a').click
+
+ within('.in_favor') do
+ expect(page).to have_content "1"
+ end
+
  find('.against a').click
 
  within('.in_favor') do