Ensure flags are 0 when performing an append or prepend operation.

This change is neccessary to support libcouchbase 2.4.4.

Change-Id: Ie404c26fdc891a9ffacdbbd4f25d19b2df0f978d
Update to latest libcouchbase (2.4.4)

Change-Id: I20f383c343e0129d52c5498766a348ba51d47186
Release 2.0.2

Change-Id: Id91a897d7c53a046ff4dd1e963294158693f97b7