Parallelize LUCreateInstance
Parallelize LUCreateInstance

Finally, instance create on different node, without iallocator, can run
in parallel. Iallocator usage still needs all nodes to be locked,
unfortunately. As a bonus most checks which could have been moved to
ExpandNames, before any locking is done.

Reviewed-by: imsnah


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