User settings

This is a pull request for issues #455 and #456.

Account dialog forms are not made very well. See [this ticket](https://github.com/meteor/meteor/issues/1822). They use click and key events to trigger submission. This is not good. What is better is to use a `<form>` element and then simply just use submit form event handler. Which then works because of the click on the button or pressing enter. Automatically. And it is better for accessibility as well. So while we are leaving account dialog forms as they are (somebody can make a pull request and fix that for them), other forms should use submit form pattern.