Organisations' filter has a title popup to explain the criteria used

Refs #124

app/views/orgas/_search.html.haml

@@ -1,9 +1,10 @@
-= search_form_for @search || Orga.search(params[:q]) do |f|
+= search_form_for Orga.search(params[:q]) do |f|
   = f.label :search, t('.label')
   %em.fa.fa-users
   = f.search_field :name_or_city_or_tags_or_description_cont_any,
     id: :q_search, size: 16,
-    placeholder: t('.title', entity: Orga.model_name.human)
+    placeholder: t('.title', entity: Orga.model_name.human),
+    title: t('.helper', entity: Orga.model_name.human)
   = f.button class: :search do
     %em.fa.fa-search
     %span.label= t '.label'

config/locales/views/en.yml

@@ -241,6 +241,7 @@ description."
     search:
       title: Find your %{entity}!
       label: Search
+      helper: You can search by name, tag, description or city. You can also filter per region, in the page's top right corner.
     index:
       title: Organisations
       new: Add an organisation

config/locales/views/fr.yml

@@ -258,6 +258,7 @@ description plus complète."
     search:
       title: Trouve ton %{entity}!
       label: Recherche
+      helper: Vous pouvez chercher par nom, mot clé, description ou ville. Vous pouvez aussi filtrer par région, en haut à droite de la page.
     index:
       title: Organisations
       new: Ajouter une organisation

config/locales/views/pt-BR.yml

@@ -242,6 +242,7 @@ descrição mais completa."
     search:
       title: Encontre %{entity}!
       label: Pesquisa
+      helper: You can search by name, tag, description or city. You can also filter per region, in the page's top right corner. (TODO)
     index:
       title: Organizações
       new: Adicione uma organização