XOP-261: Reinstate the server on 127.0.0.1 when no management
interface is defined

Signed-off-by: Jerome Maloberti <jerome.maloberti@citrix.com>
XOP-261/CA-96936: Remove Xapi_mgmt_iface.rebind

Since the management interface is listening in IPv6 automatically if
available.

Signed-off-by: Jerome Maloberti <jerome.maloberti@citrix.com>
XAPI-261/CA-96936: Make himn_only more general

To also manage the case of a localhost server.

Signed-off-by: Jerome Maloberti <jerome.maloberti@citrix.com>
XOP-261/CA-96936: Prevent multiple starts of localhost server

Signed-off-by: Jerome Maloberti <jerome.maloberti@citrix.com>
XOP-261/CA-96936: Issue a warning in case of multiple starts of HIMN server

Signed-off-by: Jerome Maloberti <jerome.maloberti@citrix.com>
Merge pull request #959 from jeromemaloberti/XOP-261

XOP-261: Reinstate the server on 127.0.0.1 when no management