Fix ajax filtering for the map markers on proposals

[antopalidi]

video-1.mov

[paarals]

related to #39

[microstudi]

Thanks @antopalidi, this is great!

In order to be super-duper excellent we should add a test to this.

I think we can add a case in the file decidim-proposals/spec/systemindex_proposals_spec.rb to check that the markerData has the corresponding filtered content.

it would be something like

context "when there are filters" do
  it "has proposals in markerData" do
    visit_component
    expect(page.body).to have_content("here some content that should appear in the json")
  end

  it "has no proposals in markerData on filtering" do
    visit_component
    uncheck "Accepted"
    expect(page.body).to have_content("here some content that should appear in the json")
  end
end

[microstudi]

good!