export for MS Office XML does not work

[Sebastian Böttger]

The export for the MS Office reference manager does not work. For example URL: /layout/msofficexml/bibtex/2<hash>/<user>[?formatEmbedded=true]

Please fix it

[Daniel Zoller]

fixed #2038

missing return statement

changed visibility of variable to private to prevent such errors

→ <<cset c08f22484ee5>>

[Lena Hettinger]

Again, MS office export does not work (error 404).

[Daniel Zoller]

wrong url should be layout/msofficexml/ not msofficexml since it is a JabRef Layout