CRUD Service support array modification with $push modifiers

[TheRusCompass]

Currently, CRUD service only allows to update (PATCH) an array in documents by adding a single record at a time using $push operator. It would be nice to add the support to $push modifiers, such as $each, $position, etc... so that those features can be exploited by CRUD service users. On the contrary, it would be recommended to add a warning banner to CRUD service documentation, so that it is clearly explained that the update interface is only similar and that it does not support all the update operators and modifiers.