PARQUET-570: Added support to write to stdout

[pilardi]

Rationale for this change

https://issues.apache.org/jira/browse/PARQUET-570

What changes are included in this PR?

Commands can now write to stdout rather than a fixed location

Are these changes tested?

There are tests for each affected files

Are there any user-facing changes?

The cli now do no require the output parameter as it writes to stdout by default