Update all needed node fields on f_mem change
Update all needed node fields on f_mem change

This fixes the setFmem function which didn't compute other related
fields after free memory change. Ideally, this should be abstracted so
that add/remove Pri and similar functions could reuse it instead of
duplicating code.
mbakke/ganeti,ganeti-github-testing/ganeti-test-1,onponomarev/ganeti,yiannist/ganeti,yiannist/ganeti,leshchevds/ganeti,andir/ganeti,leshchevds/ganeti,andir/ganeti,apyrgio/ganeti,bitemyapp/ganeti,grnet/snf-ganeti,mbakke/ganeti,onponomarev/ganeti,dimara/ganeti,mbakke/ganeti,apyrgio/ganeti,yiannist/ganeti,grnet/snf-ganeti,ganeti-github-testing/ganeti-test-1,dimara/ganeti,apyrgio/snf-ganeti,ganeti/ganeti,andir/ganeti,apyrgio/snf-ganeti,ganeti/ganeti,leshchevds/ganeti,ganeti/ganeti,bitemyapp/ganeti