Remove multi scheduler.

This patch removes the multi scheduler.  It doesn't provide any value.
The only code that exists here is for passing through requests to the
compute scheduler.  There is nothing that uses the 'default' scheduler.

The only case where this code could have been useful is if it was
patched out of tree.  At that point, it seems easier to just provide
your own scheduler driver that does what you want instead of trying to
patch this one, IMO.

DocImpact: The multi scheduler no longer exists.

Change-Id: I30902d1ce0aa5baef6693dc4a3b1057cccb27841
baremetal: Change node api related to prov_mac_address

Now prov_mac_address is going to be dropped from bm_nodes table. This patch
adjust api to the change.

A user is expected to create a node without specifying prov_mac_address, then add
an interface having the address to the node. However, for compatibility, a user
still can specify prov_mac_address when create a node. In this case, an interface
having prov_mac_address is automatically added to the node.

In response body of create, index and show, "prov_mac_address" field no longer
exists since they are showed as a member of "interfaces" fileld.

DocImpact

Change-Id: I6653829364b0a641442d45e766493180d6f2a880
Merge "baremetal: Change node api related to prov_mac_address"
Merge "Remove multi scheduler."