Support "images" command

Currently when you get either a list of images or a list of tags, they are simply printed, one per line. This is useful for piping between processes, but it would be nice to have the option to display the results in a clean table format.

Something I'm thinking about would be perhaps a UI like so:

```shell
dredge registry.example.com images --filter "myimage" --output=table
```

This would return a table containing the name and tag for all images matching the given filter. The filter would have to be required, since it could easily overload the Registry API server if it has to query every image for the list of tags.

As for the filter, I think supporting very basic wildcard matching would be enough. Unless there is feedback that regular expression matching would be something worth adding. The value "myimage" would match (case insensitive) any images with the exact name "myimage". To search for anything containing the string "myimage" you would need to add wildcards, e.g. "*myimage*". Supported wildcards should include `*` for any string, `?` for any single character, and perhaps "+" for match previous character zero or one times?

For the output argument, the following values should be supported, "plain", "table", "markdown" and "html". Where:

* `plain` would one `:` per line, no special formatting or anything like that.
* `table` would be a simple ASCII table with 2 columns, an IMAGE column and a TAG column.
* `markdown` | `html` would output the above table, rendered as either markdown or html.