Update the xtc-submit documentation
Sample a device set if XTC_DEVICE_SET undefined
Enable xtc-submit in travis CI
Adds more device sets
Merge branch 'feature/enable-xtc-job-on-travis-ci' into develop

Ack! The feature/enable-xtc-job-on-travis-ci was merged to
master and not develop.  Treating this as a HOTFIX.