Revert 9971eb85 and make multi-lines strings more readable.
(Multiline translatable strings extraction has been fixed
in koreader-misc tralua_xgettext.py.)
The Wallabag plugin's callAPI() method was attempting to parse the user supplied
URL for the Wallabag API. Unfortunately, the parse was silently failing since
the variable apiurl did not contain a complete URL. The scheme of the parsed
URL (always nil) was then used to select either http or https (default). The
result being https was always selected, regardless of the user supplied setting.
The parsed URL was switched to the variable server_url instead of apiurl but the
behavior resulting in the default selection of https when parsing fails was left
unchanged.
Previously the plugin was creating JSON by hand for authentication requests.
This would cause invalid JSON to be sent when the password contained characters
that need to be escaped (e.g. "). Using JSON.encode will result in values being
properly escaped when necessary.
