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/tasks/database.py

@@ -0,0 +1,49 @@
+# -*- coding: utf-8 -*-
+
+#   This file is part of the Calibre-Web (https://github.com/janeczku/calibre-web)
+#     Copyright (C) 2020 mmonkey
+#
+#   This program is free software: you can redistribute it and/or modify
+#   it under the terms of the GNU General Public License as published by
+#   the Free Software Foundation, either version 3 of the License, or
+#   (at your option) any later version.
+#
+#   This program is distributed in the hope that it will be useful,
+#   but WITHOUT ANY WARRANTY; without even the implied warranty of
+#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#   GNU General Public License for more details.
+#
+#   You should have received a copy of the GNU General Public License
+#   along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+from __future__ import division, print_function, unicode_literals
+
+from cps import config, logger
+from cps.services.worker import CalibreTask
+
+try:
+    from urllib.request import urlopen
+except ImportError as e:
+    from urllib2 import urlopen
+
+
+class TaskReconnectDatabase(CalibreTask):
+    def __init__(self, task_message=u'Reconnecting Calibre database'):
+        super(TaskReconnectDatabase, self).__init__(task_message)
+        self.log = logger.create()
+        self.listen_address = config.get_config_ipaddress()
+        self.listen_port = config.config_port
+
+    def run(self, worker_thread):
+        address = self.listen_address if self.listen_address else 'localhost'
+        port = self.listen_port if self.listen_port else 8083
+
+        try:
+            urlopen('http://' + address + ':' + str(port) + '/reconnect')
+            self._handleSuccess()
+        except Exception as ex:
+            self._handleError(u'Unable to reconnect Calibre database: ' + str(ex))
+
+    @property
+    def name(self):
+        return "Reconnect Database"