Merge pull request #33 from UW-GAC/return_md5 #13

Job	Run time
Run womtool: ./calc_md5.wdl	9s
Run womtool: ./md5_hex.wdl	9s
Run womtool: ./data_model_report.wdl	8s
Run womtool: ./check_md5.wdl	11s
Run womtool: ./data_table_import.wdl	8s
Run womtool: ./data_table_export.wdl	13s
Run womtool: ./backup_data_tables.wdl	13s
Run womtool: ./validate_data_model.wdl	11s
	1m 22s

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