Fix OPENDJ-1481: Consider adding method for comparing entries for exact differences, ignoring matching rules

Introduced a new object, DiffOptions, which can be used to control the behavior of diffEntries:

* the ability to perform byte-by-byte comparisons
* the ability to select which attributes are compared using an AttributeFilter
* the ability to control whether reversible (DELETE+ADD) modifications are generated, or non-reversible REPLACE modifications. For small attributes REPLACE modifications are desirable because the consume less bandwidth and result in less replication meta-data.