Added thumbnails

Merge remote-tracking branch 'cover/thumbnails' into development

# Conflicts:
#	cps/admin.py
#	cps/templates/layout.html
#	cps/ub.py
#	cps/web.py
Update join for sqlalchemy 1.4

cps/templates/search.html

@@ -1,3 +1,4 @@
+{% from 'book_cover.html' import book_cover_image %}
 {% extends "layout.html" %}
 {% block body %}
 <div class="discover">
@@ -44,7 +45,7 @@
         {% if entry.has_cover is defined %}
            <a href="{{ url_for('web.show_book', book_id=entry.id) }}" data-toggle="modal" data-target="#bookDetailsModal" data-remote="false">
             <span class="img">
-                <img src="{{ url_for('web.get_cover', book_id=entry.id) }}" alt="{{ entry.title }}" />
+                {{ book_cover_image(entry, entry.id|get_book_thumbnails(thumbnails)) }}
                 {% if entry.id in read_book_ids %}<span class="badge read glyphicon glyphicon-ok"></span>{% endif %}
             </span>
           </a>