use vignette for generating avatar urls
running stylize
set language code based on $wgUploadPath, since that contains the language subdirectory files are stored in. This is needed because some wikis have their english images stored in <bucket>/en/images instead of just <bucket>/images/
change "languageCode" to "pathPrefix" and rename variables/functions to account for this, since prefixes are not limited to just languages
changing param to path-prefix
unit tests for Vignette generated avatar urls
Merge pull request #5130 from Wikia/vignette-avatars

use vignette for generating avatar urls