Hey, great work on this so far. I just wanted to share a glitch I'm encountering in the latest version.
If you upload a file whose filename contains spaces, this plugin inserts a tag hits some issue in Flarum's Markdown implementation that does not allow spaces to be present in the URL field of a hotlink or image.
For example, if my file is named "Scene 1 Dialogue (Chinese).7z", this results in a link of "https://my.flarum.url/assets/files/2016-11-26/14:36:110-Scene 1 Dialogue (Chinese).7z", which is not parsed by Flarum's Markdown. Watch how Flarum fails to parse this valid Markdown generated by your plugin:
[Scene 1 Dialogue (Chinese).7z](https://community.langrisser.info/assets/files/2016-11-26/14:36:110-Scene 1 Dialogue (Chinese).7z)
Replacing the spaces with %20 fixes this issue and allows the links or images to be generated.
I would suggest your plugin either change spaces to underscores when saving the file or replace spaces with %20 in the URL field of a Markdown link or image. It may be easier to fix the plugin than waiting on a Markdown fix.
