decref the revision string, added to the module dict with the keys
"__version__".  This fixes a small leaks detected by Insure.

Also, instead of returning from the init should the
PyString_FromString() of "TimeStamp.error fail, we simply take
precautions by XDECREF'ing it.  Then at the end of the function, we do
a PyErr_Occurred() check and throw a fatal error if true.  This makes
this module's init function more in line with other init functions in
this package.