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/book_edit.html

@@ -1,9 +1,10 @@
+{% from 'book_cover.html' import book_cover_image %}
 {% extends "layout.html" %}
 {% block body %}
 {% if book %}
   <div class="col-sm-3 col-lg-3 col-xs-12">
     <div class="cover">
-        <img src="{{ url_for('web.get_cover', book_id=book.id, edit=1|uuidfilter)  }}" alt="{{ book.title }}"/>
+        {{ book_cover_image(book, book.id|get_book_thumbnails(thumbnails)) }}
     </div>
 {% if g.user.role_delete_books() %}
     <div class="text-center">