mathoid returns undefined for riemann-example

[LuiSlacker]

mathoid API returns undefined for Riemann example of simple AST widget.
Since mathoid seems to be accessible only within uni konstanz cluster, it's also hard to debug vmext locally (outside cluster), since mathoid has to be replaced by mathjax-node in order to work.

[physikerwelt]

Yes. I need to improve the stability of the remote server. But that is another issue.