FlashMessages template
======================
The FlashMessages template is used to render TYPO3 flash messages
as alerts in the frontend. It also resolves the alert box type
(primary, success, warning, danger) based on flash message severity.
It needs a parameter - ```flashMessages``` - which is
automatically assigned to the view by TYPO3,
so no parameter needs to be passed when rendering:
```
```
The following parameters are optionally available:
* ```class``` -> the class attribute of the surrounding
alert box(es) is extended by this value.
* ```hasCloseButton``` -> shows a close button on every alert box
```
```