Update Travis CI badge to track builds on the master branch only (#3222)
Update Travis CI badge to track builds on the master branch only (#3222)


lbeltrame/bcbio-nextgen,chapmanb/bcbio-nextgen,lbeltrame/bcbio-nextgen,chapmanb/bcbio-nextgen,lbeltrame/bcbio-nextgen,chapmanb/bcbio-nextgen