Actions (groups of buttons/icons) inconsistency

**Bug**

A number of widgets have the concept of "Actions", they are mostly collections of buttons/icons. It would be nice if we had one consistent pattern for these. For example at the moment in SpeedDial there is a specific `Action` component:

```

{
icache.set('action', 'Mailing');
}}
>

```

yet for the `Header` actions are defined like so:

```

{{
title: 'My App',
actions: [
Foo,
Bar,
Baz
]
}}

```