update version number to 0.28.1-SNAPSHOT 
update version number to 0.28.1-SNAPSHOT 
heuermh/nextflow,robsyme/nextflow,heuermh/nextflow,robsyme/nextflow,nextflow-io/nextflow,robsyme/nextflow,nextflow-io/nextflow,heuermh/nextflow,nextflow-io/nextflow,robsyme/nextflow,heuermh/nextflow,nextflow-io/nextflow,robsyme/nextflow,nextflow-io/nextflow,heuermh/nextflow