Changes Autotools testing to use HDF5_TEST_DRIVER environment
variable to avoid running tests that don't work well with several
VFDs
Restores old h5_get_vfd_fapl() testing function to setup a FAPL
with a particular VFD
Adds a macro for the default VFD name
* Updated source file copyright headers to remove "Copyright by the Board of Trustees
of the University of Illinois", which is kept in the top-level COPYING file.
