Improve UI message, if no results are found

[ruKurz]

If no results have been found, the user should be informed friendly and readable.

There should be some more background information why, no results are being displayed and maybe the user should be linked to an article, that describes how to make use of the knowledge base (Smarti).

Moreover the loading animation should not overlap the text. Also it should disappear after the requests have been finished.

[westei]

@Peym4n please also note #213

[westei]

As far as I can see their are two main cases left:

• no tokens where extracted: In this case sources that require tokens should note that a user needs to adda search term for results.
  • NOTE that because of Indicate for Queries that they are not valid without user added tokens #217 this is no longer the case for the Expertengespräche
• the Room is not available in Smarti (exception, deleted, smarti was down ...): In this case the user needs to be informed that this room is not present in the Wissensbasis

[Peym4n]

This message is shown when the widget cannot find a conversation ID or Smarti has no conversation for the ID, which means that at some point there might have been a communication problem between Rocket.Chat and Smarti.

For now I changed the message to: "This room is not available in the knowledgebase!"

In another case when no tokens exist while they are required, the widget will ask the user to add a search term (token) in order to get results.