Search improvements

[LennyLip]

1. When search, children must expand relative parent.
2. When search, children must set isFiltered too.
3. http://a5hik.github.io/angular-multi-select-tree/ test page "0.0" does not work (Node 0 with child Node 0.0 does not shown).

[Grayfox12]

Change isChildrenFiltered in multiSelectTree link function somthing like that. It helps to search at different depths in the array

function isChildrenFiltered(item, keyword) {
var flag = true;
angular.forEach(item.children, function (sub_item) {
if (sub_item.name.toLowerCase().indexOf(scope.filterKeyword.toLowerCase()) != -1) {
sub_item.isFiltered = false;
flag = false;
}else if(!isChildrenFiltered(sub_item, scope.filterKeyword)){
sub_item.isFiltered = false;
flag = false;
}
else{
sub_item.isFiltered = true;
}
});
return flag;
}