Implemented orders of a result set if order by is present and in the outermost level of a query.

On a high level, the implementation analyzes the query string, extract the outermost "order by" block, obtains all columns and their order-by orders (i.e., ascending and descending) and performs verifications of orders accordingly.  Order by ordinals are also supported.

Limitations of this implementation:
1. Order by must occur towards the end of a query that follows the last closing parenthesis (if present).
2. Columns to apply "order by" on must be present in the select column list.
3. Anything else that has not been tested against the implementation.

Also updated README.md.