Include Unit Tests

[jleechung]

• Add unit tests
  • Test files for each main function (proActiv, junction-read-count, estimate-promoter-activity)
• Include additional data files in /extdata
  • /testdata : promoter counts and activity generated with original promoter annotation and code (master branch), for Tophat2 and STAR
  • /vignette : junction files to run vignette (A549 and MCF7, 3 replicates each)
• Add promoter annotation for Gencode v34
• Addition of NEWS and CITATION files acc. to Bioconductor guidelines