<form method='GET' action='<%= url %>' class='search_form'>
  <%= text_field :search, nil, :id => 'search', :type => 'search', :name => 'search', :value => params[:search], :title => t('search_input_notice', :scope => 'refinery.admin.search') %>
  <%= hidden_field :visual_editor, nil, :name => 'visual_editor', :id => nil, :value => true  if params[:visual_editor].presence %>
  <%= hidden_field :dialog, nil, :name => 'dialog', :id => nil, :value => true if from_dialog? %>
  <%= hidden_field :callback, nil, :name => 'callback', :id => nil, :value => @callback if @callback.presence %>
  <%= submit_tag t('button_text', :scope => 'refinery.admin.search'), :name => nil %>
</form>

<form method='GET' action='<%= url %>' class='search_form'>
  <%= text_field :search, nil, :id => 'search', :type => 'search',
    :name => 'search',
    :value => params[:search],
    :title =>       t('search_input_help', :scope => 'refinery.admin.search', :query => h(params[:search])).html_safe,
    :placeholder => t('search_input_notice', :scope => 'refinery.admin.search', :query => h(params[:search])).html_safe
    %>
  <%= hidden_field :visual_editor, nil, :name => 'visual_editor', :id => nil, :value => true  if params[:visual_editor].presence %>
  <%= hidden_field :dialog, nil, :name => 'dialog', :id => nil, :value => true if from_dialog? %>
  <%= hidden_field :callback, nil, :name => 'callback', :id => nil, :value => @callback if @callback.presence %>
  <%= submit_tag t('button_text', :scope => 'refinery.admin.search'), :name => nil %>
</form>

Add a placeholder to the Search field
Add a placeholder to the Search field

1. Add placeholder
2. Make placeholder and title html_safe so that html entities can be
used.
3. New i18n string search_input_help used as tootip. Uses wording from
old search_input_notice
