Add test to check node creation with relation.
Add drop test table after test suite run. This is so we may be using other database drivers than memory.
Add support for PHP 5.3. Eloquen should work on PHP 5.3, so Baum should too.

- Ditch a ModelExtensions trait and subclass Eloquent\Model directly.
- Do not use  inside closures.
Make array syntax compatible w/PHP 5.3.x
Small test fix to actually get the first root.
Make 'updateStructure' method public as we cannot call protected methods from closure scope.
Make Baum more Postgres friendly.

- Override Eloquent\Model->newBaseQueryBuilder to return a custom Baum\Extensions\Query\Builder object.
- Implement an extension to Eloquent\Query\Builder which drops ORDER BY clause before executing an aggregate function.
- To accomplish the last point, implement a reOrderBy method which will replace the current scope ORDER BY clauses.
- Make tests Postgres friendly too.
Fix 'insideSubtree' method.
Add tests for impossible moves.
Fix error on test.
Update CHANGELOG