Disable BarterCommunity.

The missing-member message send by the BarterCommunity on the swift
port is crashing 6.1 clients.  We will disable the BarterCommunity for
version 6.2, giving people some time to upgrade their version before
enabling it again.
Disable tunneling on swift.
Merge pull request #236 from boudewijn-tribler/bugfixes

Disable BarterCommunity.