parquet.thrift uses both row / record to refer to the same concept

As we discussed on the mailing list, parquet.thrift uses the terms Record and Row to mean the same thing

Using consistent terminology will reduce the potential for confusion

The consensus on the mailing list was to use the term "row"

Mailing list link: https://lists.apache.org/thread/0gxjk4tphxls0gcrc7lt775pf8s7gtz3

**Reporter**: [Andrew Lamb](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=alamb) / @alamb
#### PRs and other links:
- [GitHub Pull Request #256](https://github.com/apache/parquet-format/pull/256)

_{**Note**: *This issue was originally created as [PARQUET-2488](https://issues.apache.org/jira/browse/PARQUET-2488). Please see the [migration documentation](https://issues.apache.org/jira/browse/PARQUET-2502) for further details.*}

Start with parquet.thrift and review pull request #256 alongside the mailing-list discussion. Check that the terminology is consistently changed from Record to row throughout the file; completion means no conflicting terms remain.

Written by the indexing model from the issue text.