Refactor aux port allocation

This move the allocation of aux port to the base vm.
Also now the free of console port during the close is in the
base VM.

An aux port is allocated to the docker container but not used
for the moment.

Ref https://github.com/GNS3/gns3-gui/issues/1039

tests/modules/vpcs/test_vpcs_vm.py

@@ -273,17 +273,6 @@ def test_get_startup_script_using_default_script(vm):
     assert vm.script_file == filepath
 
 
-def test_change_console_port(vm, port_manager):
-    port1 = port_manager.get_free_tcp_port(vm.project)
-    port2 = port_manager.get_free_tcp_port(vm.project)
-    port_manager.release_tcp_port(port1, vm.project)
-    port_manager.release_tcp_port(port2, vm.project)
-    vm.console = port1
-    vm.console = port2
-    assert vm.console == port2
-    port_manager.reserve_tcp_port(port1, vm.project)
-
-
 def test_change_name(vm, tmpdir):
     path = os.path.join(vm.working_dir, 'startup.vpc')
     vm.name = "world"
@@ -299,8 +288,5 @@ def test_close(vm, port_manager, loop):
     with asyncio_patch("gns3server.modules.vpcs.vpcs_vm.VPCSVM._check_requirements", return_value=True):
         with asyncio_patch("asyncio.create_subprocess_exec", return_value=MagicMock()):
             vm.start()
-            port = vm.console
             loop.run_until_complete(asyncio.async(vm.close()))
-            # Raise an exception if the port is not free
-            port_manager.reserve_tcp_port(port, vm.project)
             assert vm.is_running() is False