Robot structure (rebased onto develop)


This is the same as gh-1473 but rebased onto develop.

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To review that PR.
 * Make sure the following top-level commands work ```clean, build default, test-unit```
 * For test-unit, check that the unit tests under components/test/ui/java are executed.
 * For the UI tests themselves, the daily OMERO-merge-robotframework-stable build should be green.

The commands ```clean``` and ```build default``` are also run as part of the daily ```OMERO-merge-robotframework-stable``` build.

If you wish to run the tests locally and try the various ant target, please follow instructions in README. Robot framework and jython must be installed.
Note that if you wish to run the ant setup-db target, you must run ```test-compile```.

The CLI section is mainly to have the structure in place. Another Robot library (Process) will be used.

This PR replaces gh-1424

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--rebased-from #1473