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
3 files changed