As discussed in #947, links need to be redefined for Org 9. This is
fixed in
[b885dd3](b885dd308e). At
the same time, `org-mu4e-store-and-capture` is still using
`org-mu4e-store-link` only, so it doesn't work in Org 9. Fix it
by interactively calling `org-store-link` instead.