User settings

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

Instead of:

```
{{#unless isValid "current-password"}} invalid{{/unless}}
```

You could simply have a template helper which returns `invalid` string if thing is invalid, or no string if it is not. See [example](https://github.com/peerlibrary/peerlibrary/blob/development/client/publication.coffee#L1309).