Partition: pass key and object to predicate given context
Merge pull request #1686 from megawac/partition-fix

Partition: pass key and object to predicate given context
Remove unnecessary variable declaration.
Merge pull request #1687 from braddunbar/style

Remove unnecessary variable declaration.
use non-strict, non-deep equal in context test (non-strict so we can
compare booleans).
pick: use create callback
Merge pull request #1691 from megawac/chain

Simplify chain
Merge pull request #1690 from megawac/_.pick-opt

pick: use create callback
Spec null object case for _.pick and _.omit