Asynchronous filter improvements
Asynchronous filter improvements

As to comments @tshemsedinov did during codereview, several improvements
to asynchronous filter function were made:

    - Update filter function so it accepts predicate which returns result
      using callback function.
    - Change the order of arguments in filter function. Now the first
      argument is the collection of data, the second one is the
      predicate and the last is the callback.

DzyubSpirit/MetaSync,DzyubSpirit/MetaSync,metarhia/MetaSync,IvanProdaiko94/MetaSync