Add unittests

Prepare for travis testing with coverage

Add test for:
    * Example
    * Small two part Example
    * Add operation
    * And operation
    * Or operation
    * Not operation
    * Equals (==)
    * Not Equals (!=)
    * Greater Than (>)
    * Less Than (<)
    * Greater Than or Equal To (>=)
    * Less Than or Equal To (<=)