Fix url encoding when fetching remote assets

[therealgilles]

Use url.parse(fileUrl).href instead of decodeURI/encodeURI to properly encode the url if necessary.
This fixes the issue where an avatar url was getting double-encoded.

[therealgilles]

Oops, how did I not see the conflict between the url package and the url var, fix coming...

[therealgilles]

I used const urlParse = require('url').parse to avoid the conflict with existing url variables. Let me know if it's undesirable. If so, feel free to suggest an alternative names for either the library variable or the existing url variables.