Displayed username along with nickname (when they are not identical); Requested and displayed user's avatar; Made the dialog bigger for extended names.
Added a few functions to web_backend (GetImage, GetPlain) to support getting data in multiple content-types.
Added a no_avatar icon for users without avatars.
Like with TelemetryJson, we can make the implementation details private
and avoid the need to expose httplib to external libraries that need to
use the Client class.
* Change authentication system to JWT
* Address review comments
* Get rid of global variable, fix some documentations, fix a bug when verificating
* Refactor PostJson to avoid code duplication
* Rename jwt_token, add functionality to request a new JWT when getting a 401
* Take bools by value instead of const reference
* Send request again when JWT is invalid and use forward declarations
* Omit brackets
* WebService: Verify username and token; Log errors in PostJson
* Fixup: added docstrings to the functions
* Webservice: Added Icons to the verification, imrpved error detection in cpr, fixup nits
* fixup: fmt warning
