[INTERNAL] moved workspace autobuilding enable/disable logic

This logic is IDE dependent and so should not be performed inside the
core logic.

Change-Id: Idb7b6ec573d26ce57e3db9d0d0a6f6c506cac095
Reviewed-on: http://saros-build.imp.fu-berlin.de/gerrit/1888
Tested-by: Jenkins CI
Reviewed-by: Stefan Rossbach <srossbach@arcor.de>