KVM: save and remove the KVM runtime
KVM: save and remove the KVM runtime

At instance startup time we save the kvm runtime, and at stop time we
delete it. This patch also includes a function to load the kvm runtime,
which is unused yet.

Reviewed-by: iustinp


mbakke/ganeti,apyrgio/ganeti,apyrgio/ganeti,grnet/snf-ganeti,bitemyapp/ganeti,leshchevds/ganeti,grnet/snf-ganeti,mbakke/ganeti,ganeti-github-testing/ganeti-test-1,ganeti/ganeti,yiannist/ganeti,dimara/ganeti,andir/ganeti,yiannist/ganeti,ganeti/ganeti,onponomarev/ganeti,ganeti/ganeti,apyrgio/snf-ganeti,bitemyapp/ganeti,yiannist/ganeti,dimara/ganeti,apyrgio/snf-ganeti,leshchevds/ganeti,mbakke/ganeti,onponomarev/ganeti,leshchevds/ganeti,andir/ganeti,andir/ganeti,ganeti-github-testing/ganeti-test-1