types: add enumeration DType (closes #6)

- adds new dependency to package enum34 (pipy) python-enum (deb)
- let the IDE do some formatting
Property: remove value specific parameters from methods (Closes #9)

Parameters like uncertainty and unit were removed ...
- from Property.__init__
- and Property.append
DType: minor improvements

- equal enum name and enum value
- inherit from str in order to make it comparable
  DType.int == 'int' -> True
Merge pull request #22 from stoewer/master

Dtype constants and property constructor
Merge pull request #20 from asobolev/master

iterators with filter for sections, properties and values for odml.base.sectionable
Move the value paremeter of the Value init method

The value parameter of Values init method is now moved to the end of the parameter list. This means that Value(5) is now equivalent to Value(data=5).

This fixes #18
Launch test suite with setuptools.

call `python setup.py test` in order to run all unit tests.

This fixes #10
Merge pull request #25 from stoewer/master

Move the value paremeter of the Value init