Revert "qemu domain allow to set ip address, peer address and route"
    
    This reverts commit 6e244c659fb004503fd2a94319dae8fa6fecf045, which
    added support to qemu for the "peer" attribute in domain interface <ip>
    elements.
    
    It's being removed temporarily for the release of libvirt 1.3.4
    because the feature doesn't work, and there are concerns that it may
    need to be modified in an externally visible manner which could create
    backward compatibility problems.
    
     Conflicts:
       tests/qemuxml2argvmock.c - a mock of virNetDevSetOnline() was added
       which may be assumed by other tests added since the original commit,
       so it isn't being reverted.