Cleaned up Travis configuration file a bit.
Updated Travis configuration: Travis does not have Python 3.4.
Less "historical", more user-oriented doc.
The None (empty) format type should now behave as is documented for Python 3.4. This behavior is closer to the behavior of Python 2.7 than to the behavior described in the documentation of Python 2.7 (http://stackoverflow.com/questions/16525924/precise-definition-of-float-string-formatting). Not tested yet.
Better error message: formatting test values that were integers where incorrectly reported as being the values in the tested UFloat. The UFloat components are not integers.
Adapted the formatting tests to the updated None (empty) format type.
Merge branch 'master' into master_python2.3

Conflicts:
	.travis.yml
Merge branch 'master' into master_python2.3

Conflicts:
	uncertainties/__init__.py
	uncertainties/test_uncertainties.py
Fixed problem with Python 2.4.