#765 Add pushover.py module to handle sending of push notifications via the pushover service.
#765 Send a Pushover notification as well as an SMS for MOVE notifications. Currently using static user_token.
#765 Tested with User_token for another user - works fine.
#765 Update Push notification with more details to be included.
#765 Add method to mongoconnector to retrieve Pushover token for a specific user.
#765 Add method for retrieving a pushover token to the DataHandler interface.
#765 App will now check that the user has a Pushover token before trying to send a push notification.
#765 Add method to mongoconnector to add a pushover token to a user record. Will create a new record if one doesn't already exist.
#765 Add method for adding a pushover token to a user to the DataHandler interface.
#765 Accept PUSH command followed by Pushover token to register push notifications against a user.
#765 Add support for processing PUSH OFF command to turn off push notifications.
#765 Add messages for SMS responses to user.
#765 Split push notification logic out into a separate method. This can then be called recklessly where a push notification is required, and will only send one if appropriate for that user.
#765 Add push notifications for UNBLOCK and BLOCK notifications.
#765 Add methods for turning push notifications on and off for a user.
#765 Only send push notifications if PushNotification is set to 1 in the user_record.
#765 Include a URL link in the push notification which takes you straight to the SMS app. Tested on Android and iOS.
#765 Rename method to push().
#765 Process PUSH ON and PUSH OFF commands.
Merge branch 'feature/#765-Send_push_notifications_via_Pushover' into develop