Move log colors to OsmoseLog.py
Add unittest for analyser_osmosis_roundabout_reverse.py
Move some test code to Analyser.py
Replace __import__ by importlib in analyser_sax to make it working with nose
Add basic test in analyser_sax.py
Add tests for stablehash()
Skip tests needing a postgresql database if not available
Merge branch 'unittest'

This adds unit tests to Analyser, analyser_osmosis_roundabout_reverse and
analyser_sax. On analyser_sax, results are not completely checked: only the
number of errors is compared to a reference.