Re #20 - Added tests for Flow.data
Fixed data-scoping to work with a property vs a getter/setter
Re #20 Added Flow#query() tests. Refined Flow#callback and Flow tests
Re #20 - Added tests for `.args()` and `.vars` (Issue #37).
Added `.vars` (closes #37). Simplified `.args()` method functionality
Re #20 & #37 More `.vars` unit tests