OMERO.web unit and integration test fixes

This pull request restores unit test and adds integration test capabilities to OMERO.web. Unit tests should be able to be run by anyone (and all pass):

```
./build.py components/tools/OmeroWeb/build.py test
...
```

Integration tests should be able to be run under the same conditions as all other OmeroJava, OmeroPy, etc. tests in accordance with the existing documentation (http://www.openmicroscopy.org/site/support/omero5/developers/testing.html):

```
./build.py components/tools/OmeroWeb/build.py integration
...
```

Other than testing the above, there are some small changes to the OmeroPy integration test library. All those tests should be confirmed to have been run and pass or fail as per the existing status.