Improve display to change SPARQL endpoint

[vemonet]

This was a easy way to fix it, but could be improved later

I was thinking about putting the current SPARQL endpoint on the top navbar right

Hum, and a Autocomplete directly at this place
So the top bar would be:

• which URI you describe
• In which SPARQL endpoint

If it is too packed, I can just put under the URI in current UI

And add the dropdown for graph query in graph overview?

It will be better to refactor a bit to define a specific component for our different Autocomplete