mongo 2.6 query features

$mul, $min, $max, $currentDate, $bit:xor
bump mongodb and driver versions

also scala and spindle
support String subtypes in modify fields
int subtypes are bson types
bulk insert, remove in QueryExecutor
fix deprecation warnings
don't set batchSize on the cursor

Setting batchSize and sort on a cursor can cause
fewer than all of the documents to be retrieved.
Really, there's no need for the caller-facing batchSize
and the cursor's batchSize to line up. We should just
let the cursor decide what the optimal batchSize is
independent of what the caller wants to do (which
it is doing for memory reasons).