Add display scripts to travis for selenium
Fix lettuce test for py26

- Adds check_output implementation from py27 to lettuce test file
  because not included in py2.6 subprocess lib
Replace lettuce tests with pytests

- Lettuce does not support py3 and was not providing any value

[#66741700]
Fixes feature test for py33

- subprocess.check_output returns a bytes object instead of a string in
  python3

[#66741700]