Remove needless data filter in key value formatter

We don't need to filter data because we skip them anyway
if the key does not exist.

lib/lograge/formatters/key_value.rb

@@ -1,25 +1,18 @@
 module Lograge
   module Formatters
     class KeyValue
-      LOGRAGE_FIELDS = [
-        :method, :path, :format, :controller, :action, :status, :error,
-        :duration, :view, :db, :location
-      ]
-
       def call(data)
         fields = fields_to_display(data)
 
         event = fields.reduce([]) do |message, key|
-          next message unless data.key?(key)
-
           message << format(key, data[key])
           message
         end
         event.join(' ')
       end
 
       def fields_to_display(data)
-        LOGRAGE_FIELDS + (data.keys - LOGRAGE_FIELDS)
+        data.keys
       end
 
       def format(key, value)