CRUNCH-414: CSVLineReader-Threshold-Logic

JIRA: https://issues.apache.org/jira/browse/CRUNCH-414
You can simplify this code using the Configuration.getInt(key, default)[1]

[1] - https://hadoop.apache.org/docs/r2.2.0/api/org/apache/hadoop/conf/Configuration.html#getInt(java.lang.String, int)