#2436 override the function `getAttributeLabel` in `BaseActiveRecord` to receive label of the attribute, which looks like `relatedMode.attribute`, from the related model

#2436 override the function `getAttributeLabel` in `BaseActiveRecord` to receive label of the attribute, which looks like `relatedMode.attribute`, from the related model

fixes #2370

- refactored elasticsearch AR to make type and index available in
  instantiate(), issue #1313

fixes #2281

Improved `QueryBuilder::buildLimit()` to support big numbers

Change <code>array_reduce</code> with anonimous function variant to easy string collection from pieces of unions.

Using short array syntax.

Change buildUnion method to be ready to accept parameters in <code>['all' => $all, 'query' => $query]</code> format for division to "UNION" and "UNION ALL" constructions.

Change passing parameters to array with two elements – 'all' which means if we use UNION or UNION ALL construction and 'query' which is our sql query that will be at right of construction.

Forget one ";" :D

Delete some spaces from result string.

Change union method to accept also <code>$all</code> variable. TRUE means that we must results <code>UNION ALL</code> construction, FALSE – that <code>UNION</code>.

Fixed some errors – syntax with ";" after closure function and also moved building of unions queries into this function.