kauri-forms-sample: dblselect control issues

[karel]

IE only: dblselect-control doesn't work with integers, see #236)

There is a TODO in the form.submit function

[karel]

There's something wrong with integers in general: on submit they always get translated to strings.

[karel]

In [1818]:

Fix dblselect control

• properly trim to options object (+refactoring: trimToValue on Options class)
• accept wire-values that are not in the list when showAddOther is true
• fix bug in ajax request handling (in IE, $.ajax() doesn't return the xhr object!)

fixes #423