Stop abusing Map.Entry and declare our own Row type

Implementing Map.Entry<byte[], byte[]> is painful, and its just not a
good interface given that it has a setValue method.  Replace usages
of it in the NoSQL code with our own Row type that has a similar
API for the getters.

Change-Id: I9144d615e1fa9b5d0df9727c3d39b75db06f024a
Signed-off-by: Shawn O. Pearce <sop@google.com>
4 files changed