Allow passing 'limit' and 'offset' values as strings

[techniq]

Currently I am using the following koa route to pass the query string parameters down to js-data-sql

router.get('/races', function*() {
  var options = {};
  if (this.query.with) {
    options.with = Array.isArray(this.query.with) ? this.query.with : [this.query.with];
    delete this.query.with;
  }
  if (this.query.where) {
    this.query.where = JSON.parse(unescape(this.query.where));
  }
  let races = yield db.sql.findAll(models.Race, this.query, options);

  this.body = races;
});

When calling GET /races?limit=3&offset=5, it appears that knex handles limit being passed in as a string (converts it to an int) but not offset.

{ method: 'select',
  options: {},
  bindings: [ 3, '5' ],
  sql: 'select * from `race` limit ? offset ?' }

  Error: ER_PARSE_ERROR: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ''5'' at line 1

While I could parse/convert the value in the route, it seemed reasonable to have js-data-sql to handle this simple case (especially with the interplay between js-data-http and js-data-sql). I also took a look at having knex handle this, but I had trouble finding where limit was doing the string/int conversion and felt it was a better fit to have js-data-sql to handle it (because of js-data-http).

Expect an imminent PR for this ;)