Add HDF5 I/O for AnalyzerResultContainer, Fixes #7

Add HDF5 I/O for AnalyzerResultContainer, Fixes #7

- Add functions from_hdf5 and to_hdf5 to AnalyzerResultContainer.
- Add corresponding tests
- Function to_hdf5(output_file) store an entire Container in an hdf5 file using one dataset for each AnalyzerResults and using dataset attributes to store 'unit' and 'name'. The dataset Name is the AnalyzerResult 'id'.
- Function from_hdf5(input_file) load the data store in a hdf5 file and return an AnalyzerResultContainer