- giving the user a new id for each test run in order to prevent reuse of e.g. permissions data in the database
- setting the current user id because \OC\FilesView relies on \OC_User::getUser()

Remove gravatar and no-avatar functionality, prepare for default avatars even more and reword some stuff

TODO: Fix OC_Image->mimetype(), it always returns "image/png"

 - Use camelCase

 - Add some phpdoc

 - Fix some indents

 - Use some more spacing