Endianess flag not preserved with one-byte types

[jreadey]

With the one byte types, H5T_STD_(U|I)8(LE|BE), the endianess is not preserved when writing a dataset/attribute and then reading it back. E.g. test/integ/datasettest.py, testPostTypes fails if 'H5T_STD_I8' or 'H5T_STD_U8' are added to the type list.