returnVals -> returnChanges

[danielmewes]

Noticed by Nanami Ringo in http://stackoverflow.com/questions/28237225/insert-error-in-rethindb-using-node

The source is still using returnVals:
https://github.com/rethinkdb/rethinkdb-example-nodejs/blob/master/todo-angular-express/app.js#L81
https://github.com/rethinkdb/rethinkdb-example-nodejs/blob/master/todo-angular-express/app.js#L101

https://github.com/rethinkdb/rethinkdb-example-nodejs/blob/master/todo-angular-express-promise/app.js#L46
https://github.com/rethinkdb/rethinkdb-example-nodejs/blob/master/todo-angular-express-promise/app.js#L63

https://github.com/rethinkdb/rethinkdb-example-nodejs/blob/master/todo-angular-koa/app.js#L66
https://github.com/rethinkdb/rethinkdb-example-nodejs/blob/master/todo-angular-koa/app.js#L87

The argument is now called returnChanges.

(assigning to @deontologician )

[deontologician]

This was done for the express / non-promise version by #7. The promise and koa drivers still need to be done

[danielmewes]

Was fixed by #13