made omop install directory option with default to working directory ./build/omop

acmc/main.py

@@ -81,7 +81,7 @@ def main():
 	
 	# omop install
 	omop_install_parser = omop_subparsers.add_parser("install", help="Install OMOP codes within database")
-	omop_install_parser.add_argument("-d", "--omop-dir", required=True, help="Directory path to extracted OMOP downloads")
+	omop_install_parser.add_argument("-d", "--omop-dir", type=str, default=str(omop.OMOP_DB_DIR.resolve()), help="Directory path to extracted OMOP downloads")
 	omop_install_parser.add_argument("-v", "--version", required=True, help="OMOP vocabularies release version")	
 	omop_install_parser.set_defaults(func=omop_install)