adding new operators

[AndreiSemenovMinsk]

Added a way to search by multiple values:

Sample:

crud.select('users', {{'=', 'name', {'Andrey', 'Sergey'}}}, {fields = {'_id', 'name'}});

Added new operators such as:

'<>' - not '>><<' - between '<<>>' - out of '<<!>>' - out of or null '>)' - include

Sample:

crud.select('users, {{ '>><<', 'activated_at', { dateFrom, dateTo } } }, { fields = { '_id' }})