Fix logger without chaning interface

Author: zaibacu

oshino/__init__.py

@@ -0,0 +1,4 @@
+from .agents import Agent
+from .version import get_version
+
+__all__ = [Agent, get_version]

oshino/agents/__init__.py

@@ -1,6 +1,3 @@
-from logbook import Logger
-
-
 class Agent(object):
 
     def __init__(self, cfg):
@@ -21,6 +18,7 @@ def prefix(self):
         return "{0}.".format(self.name)
 
     def get_logger(self):
+        from logbook import Logger
         return Logger(self.__class__.__name__)
 
     async def process(self, event_fn):