Simple process() that follows the official guidelines for
looping over
DocumentOperations, and then calls the appropriate,
overloaded process() depending on the type of base.
Declared as final, so if you want to handle everything yourself
you should of course extend DocumentProcessor instead of
SimpleDocumentProcessor and just go about as usual.
It is important to note that when iterating over the
DocumentOperations in
com.yahoo.docproc.Processing#getDocumentOperations(), an exception thrown
from any of the process() methods provided by this class will be thrown straight
out of this here. This means that failing one document will fail the
entire batch.