Smarti widget: Provide "can not help"-information

[mrsimpson]

as per #200, queries are now always being built - but if there's no query to be executed (e. g. since no token could be extracted), there should be a meaningful information on the widget that Smarti cannot help at the moment

[westei]

depends on #217

[ruKurz]

Isn't this a duplication of: #220 or the other way around?

[westei]

if @mrsimpson agrees we can merge this into #220

[Peym4n]

See #220 (comment)