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
app-server.sh file taken from the lean branch to accomodated changes for Escenic 5.7
set_up_app_server moved after nursery configuration, because set_up_app_server decides about data-source upon the existence of DataConnector.properties file in the configuration layer ... this is important for version 5.7
Previously widget-framework had been ignored as a plugin, because it was downloaded separately and handled in wf_download_list param. Now this is just another plugin
Missing property fai_environment handled to create ece_environment property in ece conf
VOSA-69: updated doc to reflect tap interface names.
VOSA-70: suggest install genisoimage when installing vosa.
VOSA-67: Remind people to create a dir. DOH!
VOSA-68: Make the images directory if needed, when creating new machines.
Merge branch 'master' into lean

Conflicts:
	usr/share/escenic/ece-scripts/ece-install.d/content-engine.sh