OPENDJ-1560 modify/modifyrdn operations are not working in mix replication topology

There is a mismatch between code before and after r10757.
This is affecting 2.6.x and 2.6.next OpenDJ servers communicating with each other.
Before r10757, serialized ModifyMsg included a zero separator after byte arrays, after r10757 it did not.
This change is introducing back the zero separator.

ModifyMsg.java:
In getBytes_V45(), appended the zero byte separator after byte arrays + adapted decodeBody_V4() code for it.

git-svn-id: https://svn.forgerock.org/opendj/trunk@11011 41b1ffd8-f28e-4786-ab96-9950f0a78031
OPENDJ-1569 Persistent search on cn=changelog does not return updates

Code was broken by the fix for OPENDJ-1541 Persistent search on cn=changelog can return duplicates.
This change introduced a search phase enum and initialized all searches to the "initial search" phase.
Current fix consist in directly initializing persistent searches with changesOnly=true to the "persistent search" phase.

git-svn-id: https://svn.forgerock.org/opendj/trunk@11013 41b1ffd8-f28e-4786-ab96-9950f0a78031
Removed unused imports.

JEChangeNumberIndexDBTest.java:
Also removed unused field previousCookie.

git-svn-id: https://svn.forgerock.org/opendj/trunk@11014 41b1ffd8-f28e-4786-ab96-9950f0a78031