* DEV: allows to define an ariaLabel on d-button
This topic also adds this function to topic-footer-buttons, simplifies the whole logic of titile/label/arialabel in d-button and adds tests for these properties.
* typo
Usage:
```
{{d-button icon="times" label="foo.bar" isLoading=true}}
```
Note that a button loading without an icon will shrink text size to prevent button to jump in size.
A button while loading is disabled.
