Merge branch 'ls/travis-scriptify'

The scripts to drive TravisCI has been reorganized and then an optimization to avoid spending cycles on a branch whose tip is tagged has been implemented. * ls/travis-scriptify: travis-ci: fix "skip_branch_tip_with_tag()" string comparison travis: dedent a few scripts that are indented overly deeply travis-ci: skip a branch build if equal tag is present travis-ci: move Travis CI code into dedicated scripts