rails/rails — pull request #4012 by JustinCampbell (2011-12-17 13:09:52+00:00)
Title: Allow symbols to be passed as extension aliases in Mime::Type.register

I was trying to do this:

```rb
Mime::Type.register "text/markdown", :markdown, [], [:md, :mdown]
```
But that didn't work. This did:

```rb
Mime::Type.register "text/markdown", :markdown, [], ["md", "mdown"]
```
But since the symbol parameter gets turned into the extension, it was confusing to pass strings as extension aliases.

This patch lets you use strings or symbols, and allows the same for `Mime::Type.register_alias`.

I also added some tests.