Update class-option-multicheck.php

I'm using multicheck-posts option in a metabox, and I received this error:
```
Warning: in_array() expects parameter 2 to be array, string given in 
/wp-content/plugins/titan-framework/class-option-multicheck.php on line 30
```
I printed out $savedValue and found out it's a serialized string. So I unserialized it and it's working now.
Did you test multicheck options before?
Even in the demo theme ( http://demo.titanframework.net/wp-admin/post.php?post=2&action=edit ) you can't check any of the checkboxes and save it (when you save the page the become unchecked again). And it's not displaying the error probably because the debug mode is off.