Added support for the DataSource configuration of the upcoming ECE release.

- The DataSources have been merged into one, no ECE_READ_DS and _UPDATE_DS
  just the ECE_DS
- same with the ReadConnector and UpdateConnector
- This depends on the presence of the DataConnector.properties file
  in the machine's /etc/escenic/engine/common/connector/  (which is only
  there if it's a 5.7 installation
- CommunityEngine also uses the ECE_DS when it is present.

Conflicts:
	usr/share/escenic/ece-scripts/ece-install.d/app-server.sh