International docs aren't building

[Ed McDonagh]

First issue is Could not import extension sphinxcontrib.programoutput (exception: No module named 'sphinxcontrib.programoutput') but there may be others.

[Ed McDonagh]

Building all the international files - have not been built for a long time. Refs #977

→ <<cset 986b3af4dd88>>

[Ed McDonagh]

Removing reference to Celery/Flower. Refs #977

→ <<cset c2fc8fa0298e>>

[Ed McDonagh]

Adding ref #977 to changes

→ <<cset d95e967b04ac>>

[Ed McDonagh]

Merged in issue977buildtranslations (pull request #559)

Fixes #977

→ <<cset 40cac6416c8c>>