Move instance hypervisor check to ExpandNames
Move instance hypervisor check to ExpandNames

This check can be done earlier, in ExpandNames, and is needed here for
the hypervisor parameter check.

Reviewed-by: ultrotter

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