iron-image
==========
`iron-image` is an element for displaying an image that provides useful sizing and
preloading options not found on the standard `` tag.
The `sizing` option allows the image to be either cropped (`cover`) or
letterboxed (`contain`) to fill a fixed user-size placed on the element.
The `preload` option prevents the browser from rendering the image until the
image is fully loaded. In the interim, either the element's CSS `background-color`
can be be used as the placeholder, or the `placeholder` property can be
set to a URL (preferably a data-URI, for instant rendering) for an
placeholder image.
The `fade` option (only valid when `preload` is set) will cause the placeholder
image/color to be faded out once the image is rendered.
Examples:
Basically identical to `` tag:
```html
```
Will letterbox the image to fit:
```html
```
Will crop the image to fit:
```html
```
Will show light-gray background until the image loads:
```html
```
Will show a base-64 encoded placeholder image until the image loads:
```html
```
Will fade the light-gray background out once the image is loaded:
```html
```