Core htmx API test

• ajax api works with select7ms ‣

  this.server.respondWith('GET', '/test', "<div id='d1'>foo</div><div id='d2'>bar</div>")
  var div = make("<div id='target'></div>")
  htmx.ajax('GET', '/test', { target: '#target', select: '#d2' })
  this.server.respond()
  div.innerHTML.should.equal('<div id="d2">bar</div>')