Switch to HDF5Ext in one 3d/tet4 full scale test.
Adjust DataWriterHDF5Ext info dataset dimensions to match DataWriterHDF5.

For info fields, use 3 dimension dataset instead of 2 to match output
from DataWriterHDF5 output by setting the number of time steps to 1.
Fix bug in creating scatter vec.

Use DMCreateGlobalVector to create scatter Vec. This insures vector
contains the appropriate DM.