CBD-680: Count touching as intersection

Previously one bounding box touching another wasn't counted
as intersection, now it is. The reason for this change is,
that I consider a point that is on the edge of a bounding box
to be part of that bounding box.

Change-Id: I1649435845e6aee4ba23ab063d2a77dd5887fd12
Reviewed-on: http://review.couchbase.org/22982
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Filipe David Borba Manana <fdmanana@gmail.com>
CBD-681: More delete cases

Add cases for when the tree is empty or you don't supply any nodes
for deletion.

Change-Id: I089a33c157e2bc5315de5c3b8bcd9459b3dc37b6
Reviewed-on: http://review.couchbase.org/22983
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Filipe David Borba Manana <fdmanana@gmail.com>