Error is thrown when using unicode characters and attempting to download

[ariamckinley]

If I load the ViMD markdown file, which includes the following line:

### [Go to ViMD.io →](http://vimd.io)

an error is thrown:

InvalidCharacterError: The string to be encoded contains characters outside of the Latin1 range

This is because of the arrow → symbol used. The current method of downloading first encodes the markdown file in base64 then redirects to a data:// url, in order to download from the single-page-app setup. So we gotta figure out a smarter more flexible method of downloading that is capable of accepting non-standard characters.