[NUCCORE-1127] Rename "datanucleus.autoCreateSchema" to
"datanucleus.schema.autoCreateAll". Rename "datanucleus.validateSchema"
to "datanucleus.schema.validateAll". Refactor datanucleus.autoCreateXXX
to datanucleus.schema.autoCreateXXX, and datanucleus.validateXXX to
datanucleus.schema.validateXXX. Remove datanucleus.fixedDatastore since
not needed. Make use of PropertyNames in various other places instead of
hardcoded strings.