_.partition: include iterator and context arguments in the predicate
better naming
better language in tests
Swap argument order to match convention.

Fixes #1595.
Merge remote-tracking branch 'cool/master'
Tweak to taste.
Merge pull request #1601 from braddunbar/argument-order

Swap argument order to match convention.
Correct style issues.

* Use space in array/object literals.
* Convert a forgotten deepEqual candidate.
Merge pull request #1602 from braddunbar/style

Correct style issues.