Mark further failing python tests

This PR marks rather than fixes failing Python integration tests. Most of these fail on Hudson but not locally. The only test for this PR is to run the test files and note that these certain tests are picked up as xfail, something like:
```
.....x....
```
The intermittent failures may well show up as xpasses, an uppercase X.

This PR can now be tested for merging. There may or may not be local fails but the full test suite should run without error. Using the command,
```
./build.py -f components/tools/OmeroPy/build.xml integration -DMARK="not long_running"
```
should allow the test to proceed reasoinably quickly.