pep8 changes
fixed error messages
made sure that the struct version number is set when the
H5AC_cache_config_t is instantiated.
added basic test for the cache config functionality
removed properties related to trace file because, to quote the
documentation:

"The trace file feature is unsupported unless used at the direction of
The HDF Group. It is intended to allow The HDF Group to collect a
trace of cache activity in cases of occult failures and/or poor
performance seen in the field, so as to aid in reproduction in the
lab. If you use it absent the direction of The HDF Group, you are on
your own."