Add allAsync and whereAsync to a chain call

[ashlinchak]

Add async forms for all and where methods for a chain.

It'll add a possibility to use not only findAsync method at the end of the chan calls but whereAsync and allAsync. From the example below, all queries will generate the same conditions:

Person.find({ name: 'John' }).where('age >= ? OR age =< ?', [18, 20]).findAsync();
Person.find({ name: 'John' }).where('age >= ? OR age =< ?', [18, 20]).allAsync();
Person.find({ name: 'John' }).where('age >= ? OR age =< ?', [18, 20]).whereAsync();

These changes also will fix the example from readme page:

Person.find({ age: 18 }).where("LOWER(surname) LIKE ?", ['dea%']).allAsync( ... );

As allAsync will be called from model level.

Realizations of find methods in the model and in the chain are different. Do we really need to keep them in separate places?

[dxg]

👍 thanks