Add a new field to the current ResourceBuilder.

           Keyword arguments:
           field    -- field name
           arg      -- name of the attribute name in arg object (argparse)
           value    -- a default for this field, used for resource creation.
           extended -- If set to true, the current field will be display in
                       extended list mode only.
           hidden   -- If set to true, the current field won't be exposed
                       as available keys.
           e_type   -- field data type (default str): int, float, str
           required -- True if the current field is required for create
                       and update methods

def add_field(self, field, arg=None, value=None, extended=False,
                  hidden=False, e_type=str, required=None):
        """Add a new field to the current ResourceBuilder.

           Keyword arguments:
           field    -- field name
           arg      -- name of the attribute name in arg object (argparse)
           value    -- a default for this field, used for resource creation.
           extended -- If set to true, the current field will be display in
                       extended list mode only.
           hidden   -- If set to true, the current field won't be exposed
                       as available keys.
           e_type   -- field data type (default str): int, float, str
           required -- True if the current field is required for create
                       and update methods
        """
        if required is None:
            required = self._required
        if arg is None:
            arg = re.sub('(?!^)([A-Z]+)', r'_\1', field).lower()
        self._fields[field] = {
            'field': field,
            'arg': arg,
            'value': value,
            'extended': extended,
            'required': required,
            'e_type': e_type,
            'hidden': hidden
        }