v1/folders/rescan: argument forceupdate by default true

[ubacher]

The docu for v1/folders/rescan says the parameter forceupdate is by default false. It turns out that it is by default true.

[Mario]

Doku is right, code was wrong. Fixed for the next release.

Tip: Always specify parameters the way you want them. This protects you from later changes in the API.