Make findall support server side filtering

Instead of listing all servers and doing clientside filtering, use the servers
filtering on name.the server's list already supports filtering
so just pass a search_opts dictionary into list().

This should speed up nova commands when a user has large numbers of servers.

Change-Id: I6deea8523754ff213f43bd059fb00f34fc0e1a12
Closes-Bug: #1202179
Merge "Make findall support server side filtering"