hdf5_ep

[svn-r16652] Bug fix #1503 - H5Iget_type failed unexpected when an invalid ID was passed in.  I put 
some argument check in the internal function H5I_find_id and took out the assertion check.
I also removed the argument check in H5Iis_valid because it's in H5I_find_id now.

Tested on jam and linew - simple change.