Added a script that downloads the project repositories if necessary -- we do not store the project repositories in the main defects4j repo.
Added a script that downloads the project repositories if necessary -- we do not
store the project repositories in the main defects4j repo.

rjust/defects4j,rjust/defects4j,jose/defects4j,jose/defects4j,rjust/defects4j,rjust/defects4j,jose/defects4j,jose/defects4j