gns3server crash if virtualbox is not installed

[anubisg1]

Virtual box is a recommended plugin, not a mandatory requirement for gns3.

how to reproduce the crash:

1. vboxwrapper is installed
2. vitualbox is NOT installed
3. open the gui --> settings --> VirtualBox VMs

[E 140724 10:07:23 base:277] uncaught exception <class 'gns3server.modules.virtualbox.virtualbox_error.VirtualBoxError'>
    Traceback (most recent call last):
      File "/usr/lib/python3.3/site-packages/gns3server/modules/base.py", line 275, in _decode_request
        self.modules[self.name][destination](self, params)
      File "/usr/lib/python3.3/site-packages/gns3server/modules/virtualbox/__init__.py", line 751, in vm_list
        self._start_vbox_service()
      File "/usr/lib/python3.3/site-packages/gns3server/modules/virtualbox/__init__.py", line 134, in _start_vbox_service
        self._vboxwrapper.start()
      File "/usr/lib/python3.3/site-packages/gns3server/modules/virtualbox/vboxwrapper_client.py", line 149, in start
        self.wait_for_vboxwrapper(self._host, self._port)
      File "/usr/lib/python3.3/site-packages/gns3server/modules/virtualbox/vboxwrapper_client.py", line 170, in wait_for_vboxwrapper
        last_exception))
    gns3server.modules.virtualbox.virtualbox_error.VirtualBoxError: Couldn't connect to vboxwrapper on 127.0.0.1:11525 :[Errno 111] Connection refused
[I 140724 10:07:23 base:218] ZeroMQ client (virtualbox) sending JSON-RPC custom error: uncaught exception <class 'gns3server.modules.virtualbox.virtualbox_error.VirtualBoxError'>: Couldn't connect to vboxwrapper on 127.0.0.1:11525 :[Errno 111] Connection refused
    Traceback (most recent call last):
      File "/usr/lib/python3.3/site-packages/gns3server/modules/base.py", line 275, in _decode_request
        self.modules[self.name][destination](self, params)
      File "/usr/lib/python3.3/site-packages/gns3server/modules/virtualbox/__init__.py", line 751, in vm_list
        self._start_vbox_service()
      File "/usr/lib/python3.3/site-packages/gns3server/modules/virtualbox/__init__.py", line 134, in _start_vbox_service
        self._vboxwrapper.start()
      File "/usr/lib/python3.3/site-packages/gns3server/modules/virtualbox/vboxwrapper_client.py", line 149, in start
        self.wait_for_vboxwrapper(self._host, self._port)
      File "/usr/lib/python3.3/site-packages/gns3server/modules/virtualbox/vboxwrapper_client.py", line 170, in wait_for_vboxwrapper
        last_exception))
    gns3server.modules.virtualbox.virtualbox_error.VirtualBoxError: Couldn't connect to vboxwrapper on 127.0.0.1:11525 :[Errno 111] Connection refused
     for call id 74938726-3729-4178-8ecc-181055e71f88

gns3 should account for the possibility of not having virtual box and display an error (even disable the virtual box section in the settings) instead of crashing

[grossmj]

This should have been fixed now (you will need to use vboxwrapper version >= 9.1)