Ant targets:
clean - removes build, target and downloads (downloads should be autocleaned anyway)
getDependencies - gets stanford corenlp and log4j
jar - builds the jar -- need to provide:
-Dmain_path=path_to_main_class (the only main currently existing is at com.nextcentury.TripletExtraction.TestDriver)
-Djar_name=base_name_of_resulting package (dont include the .jar.... defaults to package resulting in package.jar)