bgp: add __init__.py files

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
bgp: fix connect timeout error

RROR 2014-04-23 11:54:59,239 hub 58 hub: uncaught exception: Traceback (most recent c\
all last):
  File "/Users/fujita/git/ryu/ryu/lib/hub.py", line 50, in _launch
    func(*args, **kwargs)
  File "/Users/fujita/git/ryu/ryu/services/protocols/bgp/base.py", line 239, in start
    self._run(*args, **kwargs)
  File "/Users/fujita/git/ryu/ryu/services/protocols/bgp/peer.py", line 448, in _run
    self._connect_loop(client_factory)
  File "/Users/fujita/git/ryu/ryu/services/protocols/bgp/peer.py", line 820, in _conne\
ct_loop
    bind_address=bind_addr)
  File "/Users/fujita/git/ryu/ryu/services/protocols/bgp/base.py", line 354, in _conne\
ct_tcp
    return sock
UnboundLocalError: local variable 'sock' referenced before assignment

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>