Add method to list all leases a user or project has access to.
Add method to list all leases a user or project has access to.

Also adjust some of the existing lease enumeration functions to take
a lease type selector argument.  Here is the comment above the
new GetAllowedLeases() method:

 Return a list of leases for which a user OR entire project has access.

 Permissions are determined as follows:
 * The owner of a lease always has full (RW) access
 * Users in a project with group_root or above trust always have full (RW)
   access to leases associated with that project.
 * Explicitly granted per-user and per-project permissions are extracted
   from the lease_permissions tables.

 Arguments:
 * upid - User OR Project object to lookup lease access for.
 * type - Optional lease type selector.  Restrict results to this type
          of lease.

 Returns: Array of lease objects the given principal (user or project) has
          access to.  To each of these lease objects, an "allow_modify"
          boolean is set, accessible via $leaseobj->allow_modify().

nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome