handle FileAlreadyExist' exception when driver tries to add certain files twice.
DBC model and other .NET example change
DBC model change 2
undo the handling of FileAlreadyExistsException exception
Merge branch 'master' of https://github.com/Microsoft-CISL/REEF into YingdaReef

Conflicts:
	reef-examples/src/main/java/com/microsoft/reef/examples/retained_evalCLR/Launch.java
remove REEF_JAR_FILE to be comply with recent changes
Merge pull request #663 from Microsoft-CISL/YingdaReef

DBC model