Added HDF5HandlerAmuse

I need a way to tests all amuse units.
```
test_flushbuffers (__main__.test_HDF5HandlerAmuse) ... Ok
test_flushbuffers_and_trim (__main__.test_HDF5HandlerAmuse) ... Ok
test_group_and_dataset_creation (__main__.test_HDF5HandlerAmuse) ... Ok
test_group_and_dataset_creation_after_closing (__main__.test_HDF5HandlerAmuse) ... Ok
test_group_creation (__main__.test_HDF5HandlerAmuse) ... Ok
test_group_creation_after_closing (__main__.test_HDF5HandlerAmuse) ... Ok
test_hdf5file_dataset_creation (__main__.test_HDF5HandlerAmuse) ... Ok
test_hdf5file_dataset_creation_after_closing (__main__.test_HDF5HandlerAmuse) ... Ok
test_multiple_datasets (__main__.test_HDF5HandlerAmuse) ... Ok
test_sum_flts_almostequal1 (__main__.test_HDF5HandlerAmuse) ... Ok
test_sum_flts_almostequal2 (__main__.test_HDF5HandlerAmuse) ... Ok
test_sum_flts_almostequal3 (__main__.test_HDF5HandlerAmuse) ... Ok
test_sum_flts_almostequal4 (__main__.test_HDF5HandlerAmuse) ... Ok
test_sum_flts_almostequal5 (__main__.test_HDF5HandlerAmuse) ... Ok
test_sum_flts_almostequal6 (__main__.test_HDF5HandlerAmuse) ... Ok
test_sum_flts_almostequal7 (__main__.test_HDF5HandlerAmuse) ... Ok
test_sum_ints (__main__.test_HDF5HandlerAmuse) ... Ok
test_trimming (__main__.test_HDF5HandlerAmuse) ... Ok
test_flushbuffers (__main__.test_HDF5Handler_ndarrays) ... Ok
test_flushbuffers_and_trim (__main__.test_HDF5Handler_ndarrays) ... Ok
test_group_and_dataset_creation (__main__.test_HDF5Handler_ndarrays) ... Ok
test_group_and_dataset_creation_after_closing (__main__.test_HDF5Handler_ndarrays) ... Ok
test_group_creation (__main__.test_HDF5Handler_ndarrays) ... Ok
test_group_creation_after_closing (__main__.test_HDF5Handler_ndarrays) ... Ok
test_hdf5file_dataset_creation (__main__.test_HDF5Handler_ndarrays) ... Ok
test_hdf5file_dataset_creation_after_closing (__main__.test_HDF5Handler_ndarrays) ... Ok
test_multiple_datasets (__main__.test_HDF5Handler_ndarrays) ... Ok
test_sum_flts_almostequal1 (__main__.test_HDF5Handler_ndarrays) ... Ok
test_sum_flts_almostequal2 (__main__.test_HDF5Handler_ndarrays) ... Ok
test_sum_flts_almostequal3 (__main__.test_HDF5Handler_ndarrays) ... Ok
test_sum_flts_almostequal4 (__main__.test_HDF5Handler_ndarrays) ... Ok
test_sum_flts_almostequal5 (__main__.test_HDF5Handler_ndarrays) ... Ok
test_sum_flts_almostequal6 (__main__.test_HDF5Handler_ndarrays) ... Ok
test_sum_flts_almostequal7 (__main__.test_HDF5Handler_ndarrays) ... Ok
test_sum_ints (__main__.test_HDF5Handler_ndarrays) ... Ok
test_trimming (__main__.test_HDF5Handler_ndarrays) ... Ok

----------------------------------------------------------------------
Ran 36 tests in 4.468s
```