bridge kernel python 2 issue

[cyrush]

def display_images(info):
    nonlocal server

python 2 doesn't support the nonlocal keyword

[cyrush]

  File "/Users/harrison37/Work/github/alpine-dav/ascent/build-debug/python-modules/ascent/bridge_kernel/server.py", line 71
    nonlocal server
                  ^
SyntaxError: invalid syntax