PySection: doc for mixin and bindings
added bindings for DataTag
Merge branch 'master' into development
added python mixin and docstrings for DataTag
added doc references to the main sphinx documentation
added tests for the DataTag
Merge pull request #28 from stoewer/documentation

PySection: doc for mixin and bindings

docs docs docs!
[test] DataArray: modify IO tests to prepare for 'data' change

With 'data' the DataArray.data property is meant
PyDataArray: Remove data property and its docstrings
DataArray: re-add 'data' property which now returns a DataSet

Or it returns None if there is no data associated with the object.
[test] DataArray: add test for renewed 'data' property
DataArray.create_data: Use data property to return the DataSet

Instead of create a new DataSet object
DataSet: Add 'shape' property to return data dimensions
DataSet: Add __array__ array 'interface' method
[test] Test for DataSet's __array__
[doc] Add DataSet to documentation
Merge pull request #29 from gicmo/data_io1

Change DataArray's data property to return a DataSet

Thanks
DataTag: all tests passed
Merge branch 'development'