control: Add 'less_than' modifier

This modifier allows one to return a value from a table based on if the
value passed to it is less than the table key value.

For example:

"modifier": {
  "operator": "less_than",
  "value": [
    {
       "arg_value": 30,
       "parameter_value": 300
    },
    {
       "arg_value": 40,
       "parameter_value": 400
    },
    {
       "arg_value": 50,
       "parameter_value": 500
    }
  ]
}

With the above config, it would do the following:
* value less than 30:  return 300
* else if value less than 40: return 400
* else if value less than 50: return 500
* else: return a default value based on data type of parameter_value

Signed-off-by: Matt Spinler <spinler@us.ibm.com>
Change-Id: I8b47341f41723c0cdf1ee2786526550fc24551f9
diff --git a/control/json/config_base.hpp b/control/json/config_base.hpp
index 4f7a425..5bfb9f2 100644
--- a/control/json/config_base.hpp
+++ b/control/json/config_base.hpp
@@ -102,7 +102,6 @@
         return _profiles;
     }
 
-  protected:
     /**
      * @brief Determines the data type of a JSON configured parameter that is
      * used as a variant within the fan control application and returns the
@@ -143,6 +142,7 @@
             "Unsupported data type for JSON object's value");
     }
 
+  protected:
     /* Name of the configuration object */
     std::string _name;