Add option to disable raw/obs mode output

Created by: dopsi

In 777151d9, a new raw output file parameter is added to virgo's observe function. A typical use of the function can be seen here.

The current behavior is to unconditionally write both the raw and processed output to the output directory. In order to disable this option, it is required to use /dev/null.

This change introduces the ability to control this behavior by automatically setting the proper filename based on a flag.