Multicheckbow is not working with JSON objects

Issue similar to #88

I fixed it in

angular-formly-templates-bootstrap/src/types/multiCheckbox.js

Lines 36 to 42 in 26ec0f5

	const modelValue = $scope.model[opts.key];
	if (angular.isArray(modelValue)) {
	const valueProp = to.valueProp || 'value';
	angular.forEach(to.options, function(v, index) {
	$scope.multiCheckbox.checked[index] = modelValue.indexOf(v[valueProp]) !== -1;
	});
	}

replacing

$scope.multiCheckbox.checked[index] = modelValue.indexOf(newOptionsValues[index][valueProp]) !== -1;

by

$scope.multiCheckbox.checked[index] = modelValue.map(function(t){return t[valueProp];}).indexOf(newOptionsValues[index][valueProp]) !== -1;

And in the setModel function

function setModel() {
              $scope.model[opts.key] = [];
              angular.forEach($scope.multiCheckbox.checked, function (checkbox, index) {
                if (checkbox) {
                  $scope.model[opts.key].push(to.options[index]);
                }
              });