304 - Refactor _author partial for clarity

[Janell-Huyck]

Fixes #304

This PR refactors the _authors partial at app/views/partials/_author.html.erb for clarity. It does not change the calls to the JavaScript functions to add or delete authors. There is one visible change from the original version. The original version had a blank space after the first author because it includes an invisible "remove" button. The refactored version does not include the blank button.

The layout issues will be addressed with issue #305.

Refactored code:
(Included to make it easier to read)

<div id="author_group">
    <% if publication.author_first_name.empty? && publication.author_last_name.empty? %>
    <% publication.author_first_name << '' %>
    <% publication.author_last_name << '' %>
    <% end %>

    <% publication.author_first_name.each_with_index do |_, index| %>
    <div class="form-row" id="author_<%= index %>">
        <div class="col-md-5">
            <%= label_tag(:author_first_name, author_or_artist_label + ' First Name', class: "required") %>
            <%= text_field_tag "#{name}[author_first_name][]", publication.author_first_name[index], required: true, class: "form-control form-group" %>
        </div>
        <div class="col-md-5">
        <%= label_tag "#{name}_author_last_name_#{index}", "Author Last Name", class: "required" %>
        <%= text_field_tag "#{name}[author_last_name][]", publication.author_last_name[index], required: true, class: "form-control form-group" %>
        </div>
        <% if index > 0 %>
        <div class="col-md-2">
            <%= button_tag "Remove Author", type: "button", onclick: "removeAuthor('author_#{index}')", class: "form-control form-group bg-danger text-white" %>
        </div>
        <% end %>
    </div>
    <% end %>
</div>
<%= button_tag "Add Author", type: "button", id: "add_author_btn", onclick: "addAuthor('#{name}')", class: "btn btn-primary" %>