Add travis config for upstream

Will require new secure env vars for the upstream fork
Make travis script executable
Merge pull request #40 from sneakypete81/travis_for_upstream
Updated secrets for photo/openphoto-python test server
Add Travis status to README
Update README to use Python3-style print function
Add Pylint to Travis test run.

Results are written to the log for information only.
Pylint errors won't cause test failures.
Run pylint after the main tests are complete
Merge pull request #43 from sneakypete81/travis_pylint

Get Travis to run Pylint
Merge branch 'python3' into development
Merge remote-tracking branch 'upstream/master' into unit_tests