Lower batch size to 1

A customer is experiencing OOM kills, and we are investigating. Reducing
the batch size may reduce memory usage, but at a minimum allows us to
introduce a debug mode (coming in future commit) where we print the
filename we are analyzing before we analyze.

Author: brynary

bin/eslint.js

@@ -184,7 +184,7 @@ var analysisFiles = runWithTiming("buildFileList", function() {
 
 function analyzeFiles() {
   var batchNum = 0,
-      batchSize = 100,
+      batchSize = 1,
       batchFiles,
       batchReport;