[maven-release-plugin] prepare release 7.4.0
[maven-release-plugin] prepare release 7.4.0

fnothaft/Hadoop-BAM,ryan-williams/Hadoop-BAM,cmnbroad/Hadoop-BAM,fnothaft/Hadoop-BAM,ryan-williams/Hadoop-BAM,HadoopGenomics/Hadoop-BAM,fnothaft/Hadoop-BAM,cmnbroad/Hadoop-BAM,HadoopGenomics/Hadoop-BAM,HadoopGenomics/Hadoop-BAM