transformed prsr.js to a module - moved output and log filename to app.js

some other refactoring also was done.
 all stats are gatheres in 'stats' object,

 also there is 'bads' object. it contains list of correct nginx-logged queries,
 that, however,  produce a nonsense result being passed thru 'prsr'

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 so, currently we have prsr.js module,
 that provides single method 'parseNginx: function(filename, callback([2])'.
 see example usage at app.js
  not sure if 'filename' relative to prsr module or calling code.