wip: Implement a scheduler to run recurring tasks (such as z-push-gabsync) (#123)

* add scheduler container for gabsync
Adds a general scheduler container to trigger tasks within containers.
Also adds gabsync to zpush image
* make scheduler dynamic
execute each cron job once at startup to see if they would succeed
* remove services scripts from core container (now is part of the scheduler)
* add "CRONDELAY" for tasks that should not be executed at startup
* add documentation
* clear out crontab at startup

core/Dockerfile

@@ -54,7 +54,6 @@ ENV LANG=en_US.UTF-8
 ENV SERVICE_TO_START=server
 
 COPY defaultconfigs/ start-service.sh /kopano/
-COPY services /kopano/services
 
 WORKDIR /kopano/path
 

core/services/kopano-public-store.sh

@@ -1,8 +0,0 @@
-#!/bin/bash
-
-set -eo pipefail
-
-exec dockerize \
-	-wait tcp://localhost:236 \
-	-timeout 360s \
-	kopano-storeadm -h default: -P

core/services/kopano-users.sh

@@ -1,8 +0,0 @@
-#!/bin/bash
-
-set -eo pipefail
-
-dockerize \
-	-wait tcp://localhost:236 \
-	-timeout 360s
-while true; do kopano-cli --sync && sleep 3600; done

core/start-service.sh

@@ -45,8 +45,6 @@ server)
 	else
 		DB_CONN="tcp://$KCCONF_SERVER_MYSQL_HOST:$KCCONF_SERVER_MYSQL_PORT"
 	fi
-	/kopano/services/kopano-public-store.sh &
-	/kopano/services/kopano-users.sh &
 	dockerize \
 		-wait file://"$KCCONF_SERVER_SERVER_SSL_CA_FILE" \
 		-wait file://"$KCCONF_SERVER_SERVER_SSL_KEY_FILE" \