cmdlib: Node whitelist support for allocation request
cmdlib: Node whitelist support for allocation request

Forward the node whitelist to the iallocator plugin.

Signed-off-by: Michael Hanselmann <68b67885ff74281219b4a4be33cc20fd45078d7c@google.com>
Reviewed-by: Guido Trotter <f62ca4d5358bdaeef0e50e57f9f7e231de63727e@google.com>

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