Update version 2.9.15

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/rbamtools@90 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
Initial import of new test_bam_header.r

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/rbamtools@91 edb9625f-4e0d-4859-8d74-9fd3b1da38cb