Typo: Callback function undefined

This is a typo where the callback's name should be cb() and not callback(). It was throwing an error about this undefined function when it encountered an error.
Unused variable insertCollection

I kept getting an error about insertCollection being undefined. When I looked into it, I noticed insertCollection was set to 'undefined' and never used in this function. As a result, it wasn't properly throwing an error when it should have because it kept getting stuck on this undefined variable.
ignore undefined or null values. fixes #300
Merge pull request #309 from glenselle/patch-1

Typo: Callback function undefined
Merge pull request #310 from glenselle/patch-2

Unused variable insertCollection
allow a defaults argument to be passed into the initialize function
0.10.0-rc4
bump minimum waterline-schema version
add defaults key to config #306
use createEach instead of an async create
if an array is used with create, try and use createEach falling back to create
Added some notes, and a stub fn in deferred.
Further stubbed out the acyclic traversal algorithm for populateDeep.
Refactor into a util.
First fixes, beginnings of test for graph traversal util.
Pretty dern good, but could be smarter.
Made acyclic traversal smarter-- uses 'via' to eliminate unnecessary lookups in certain cases.
Improved tests for util/acyclicTraversal.
update lifecycle callback names
port over adapter whitelist functionality