fix bug where siblings were deleted; no error when delete matches nothing
move handling of Negate to planner (Fixes #85)
Merge pull request #250 from mossprescott/repl-quick-fix

fix bug where siblings were deleted; no error when delete matches nothin...
Merge pull request #251 from mossprescott/85-negate-in-planner

move handling of Negate to planner (Fixes #85)
Merge remote-tracking branch 'upstream/master' into generalizing-to-Workflow

Conflicts:
	src/test/scala/slamdata/engine/physical/mongodb/planner.scala