Add a new fig command for retrieving the locally bound port of a service.

Signed-off-by: Daniel Nephin <dnephin@gmail.com>

fig/cli/errors.py

@@ -9,6 +9,8 @@ class UserError(Exception):
     def __unicode__(self):
         return self.msg
 
+    __str__ = __unicode__
+
 
 class DockerNotFoundMac(UserError):
     def __init__(self):