browserify: WebSocketTransport: Add exports and require to work with Node.js.

Change-Id: I840e4624f21152c7c8b008a75912a6fe89947285
tests: Rename global variable ndn to ndn1 to not conflict with global namespace ndn.

Change-Id: I62a00dfeaff7d2010d73988e06e394cc0ca16d97