add executeAndFetchTableLazy

Resolves https://github.com/aaberg/sql2o/issues/49

This probably needs tests before it is merged. Posting pull request for now so @aaberg can review.

Basic usage:
```
        LazyTable lt = executeAndFetchTableLazy();

        // can get name
        String name = lt.getName();

        // or columns
        List<Column> cols = lt.getColumns();

        // or iterate through rows (java 7)
        try (ResultSetIterable<Row> iterable = lt.getRows()) {
            for (Row item : iterable) {
                 // do stuff here
            }
        }
```