Enable npm test
preOrder traversal and tests
Remove unused arg
Serializes without properties prefixed with '_', removes parent.uuid assignment.
preOrderPrevious + Changes based on review
Merge branch 'feature/preorder-traversal' into feature/serialize-without-privates

Conflicts:
	test/tree-spec.js
Merge pull request #4 from evanrs/feature/serialize-without-privates

Serializes without privates, removes parent reference
Merge pull request #3 from evanrs/feature/preorder-traversal

Adds preorder traversal.
Merge branch 'develop' into move-lodash-sugar

Conflicts:
	test/tree-spec.js