JAVA-403 allow user to specify UUID format
Reverted formatting changes that are not related to the work at hand.
Using BsonInput.mark/reset and removed BsonInput.setPosition.
Renamed CodecHelper to UUIDCodecHelper and made it non-public
Lower-casing UUID in all class names to match UuidRepresentation.
Moved LimitedLookaheadMarkSpecification into bson module
Fixed problem with use of static fields in LimitedLookaheadMarkSpecification so that tests all pass with JsonWriter/JsonReader
Added BsonReader.peekBinarySubType as a more efficient alternative to BsonReader.mark/reset, to avoid
a double copy of the byte array.