Merge branch 'master' into devel

* master:
  Bump version number
  Update scDD reference
  Add addGeneLengths to vignette
  Add addGeneLengths tests
  Add addGeneLengths function
  Update Roxygen version
  Update README
  Add bioc-devel to Travis

From: Luke Zappia <lazappi@users.noreply.github.com>

git-svn-id: file:///home/git/hedgehog.fhcrc.org/bioconductor/trunk/madman/Rpacks/splatter@126415 bc3139a8-67e5-0310-9ffc-ced21a209358