1. add ncmpi_put_att and ncmpi_get_att and their Fortran 77 APIs.
2. Note they are not "flexible" APIs, just correspond to netCDF nc_put_att and nc_get_att.
3. add tests for these APIs in test/nc_test
4. add back tests for flexible APIs. They are now just a sanity test, no actual derived datatype is used.


git-svn-id: https://svn.mcs.anl.gov/repos/parallel-netcdf/trunk@1597 c368ceb8-fd28-0410-a457-e46ee1d7cd4a