Investigate loading hasOne and belongsTo using join

[techniq]

Currently all relations loaded via with are done so using a subsequent select * from relationTable where id in (...). For hasOne and belongsTo relations, loading these relatoins should be possible and more performant by adding a left join to the original query for each of these relation types and distributing the columns to the primary entity and each relation property based on the table name prefix of the column.

This was requested at http://stackoverflow.com/questions/36358836/js-data-sql-dssqladapter-create-inner-join

[jhoelter]

+1 for this feature, as this is a complete killer for a production application

[jmdobry]

js-data-sql would probably just need to override some methods in js-data-adapter to make this happen.