model: warn if BASE_DIRECTORY doesn't exists

Without it pretty much nothing can work. So it's good to notice it.
model tests: fix usage of .affects

.affects is now a VA, so need to use it via .value.
Merge branch 'master' of vpn.delmic.com:odemis
Update chamber position before future returns
Small changes in extra testcases
Merge branch 'master' of delmic-server.local:odemis