Only register gdrive callback if gdrive is enabled

With enabled gdrive return on change if no watch callback is configured, instead of send request to google drive

cps.py

@@ -31,7 +31,7 @@ else:
     sys.path.append(os.path.join(os.path.dirname(os.path.abspath(__file__)), 'vendor'))
 
 
-from cps import create_app
+from cps import create_app, config
 from cps import web_server
 from cps.opds import opds
 from cps.web import web
@@ -64,7 +64,8 @@ def main():
     app.register_blueprint(about)
     app.register_blueprint(shelf)
     app.register_blueprint(admi)
-    app.register_blueprint(gdrive)
+    if config.config_use_google_drive:
+        app.register_blueprint(gdrive)
     app.register_blueprint(editbook)
     if kobo_available:
         app.register_blueprint(kobo)

cps/gdrive.py

@@ -123,10 +123,12 @@ def revoke_watch_gdrive():
 
 @gdrive.route("/gdrive/watch/callback", methods=['GET', 'POST'])
 def on_received_watch_confirmation():
+    if not config.config_google_drive_watch_changes_response:
+        return ''
     if request.headers.get('X-Goog-Channel-Token') != gdrive_watch_callback_token \
             or request.headers.get('X-Goog-Resource-State') != 'change' \
             or not request.data:
-        return redirect(url_for('admin.configuration'))
+        return '' # redirect(url_for('admin.configuration'))
 
     log.debug('%r', request.headers)
     log.debug('%r', request.data)

cps/gdriveutils.py

@@ -20,6 +20,8 @@ from __future__ import division, print_function, unicode_literals
 import os
 import json
 import shutil
+import chardet
+import ssl
 
 from flask import Response, stream_with_context
 from sqlalchemy import create_engine