Gns3-converter

* Force NIO connections to be lowercase (Fixes 10 again)

* Fix issue with cloud connections not connecting when more than one cloud
is used in a topology (Fixes 10)

* Fix incorrect topology path when running on Windows (Fixes 9)

* Fix error when there are no VirtualBox nodes (Fixes 8)

* Implement snapshot support based upon legacy snapshot system.
This will not currently work until we can confirm how snapshots will work
in GNS3 v1.0
* Change how we retrieve the version number for use in setup.py
* Tidy up Legacy and JsonTopology classes
* Add support for converting VirtualBox nodes
* Ensure node labels are placed in the correct place

* Implement new JSONTopology class
* Ignore NOTES that have an interface property (old interface labels)
* Don't create the project in a subdirectory, get the topology name from
the project directory and make the input file optional (Fixes 3)
* Correct the path for the config files in the converted topology (Fixes 7)
* Process frame relay interfaces and mappings (Fixes 6)
* Improve error and debug printing
* Convert hx and hy values for label positions