Description
Most FileSource implementations support the "inputConf" method:
http://crunch.apache.org/apidocs/0.8.3/org/apache/crunch/Source.html#inputConf%28java.lang.String,%20java.lang.String%29
This method allows consumers to set/override one configuration option at a time. If this were implemented in the CSVFileSource, consumers could instantiate a file source with one of the simple constructors and modify only the options they need customized, instead of specifying all options using defaults in the full constructor.