Write a DocumentWriteOperation using WriteHostBatcher

[rjrudin]

As a Java Client user
I want to (issue title)
So that I can write a library that abstracts whether WriteBatcher is used or just a DocumentManager so that either ML8 or ML9 can be used

• I noticed that WriteBatcher, at least on master, does not have a method that takes a DocumentWriteOperation.
• I think DocumentWriteOperation is one of the better features of the Java Client, since it encapsulates a write request in a single object. Could an add(DocumentWriteOperation) method be added to WriteBatcher?

[vivekmuniyandi]

QA and Docs:

Have added an overload in WriteBatcher for adding a DocumentWriteOperation

WriteBatcher add(DocumentWriteOperation writeOperation);