console: run_script_once is broken

[mhils]

Steps to reproduce the problem:

1. mitmproxy
2. n g enter
3. | script.py

What is the expected behavior?

No crash.

What went wrong?

user@user-ubuntu:~$ mitmproxy
Traceback (most recent call last):
  File "/media/sf_git/mitmproxy/mitmproxy/console/master.py", line 317, in run_script_once
    s = script.Script(command)
AttributeError: module 'mitmproxy.script' has no attribute 'Script'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/media/sf_git/mitmproxy/mitmproxy/console/master.py", line 498, in run
    self.loop.run()
  File "/usr/local/lib/python3.5/dist-packages/urwid/main_loop.py", line 278, in run
    self._run()
  File "/usr/local/lib/python3.5/dist-packages/urwid/main_loop.py", line 376, in _run
    self.event_loop.run()
  File "/usr/local/lib/python3.5/dist-packages/urwid/main_loop.py", line 682, in run
    self._loop()
  File "/usr/local/lib/python3.5/dist-packages/urwid/main_loop.py", line 719, in _loop
    self._watch_files[fd]()
  File "/usr/local/lib/python3.5/dist-packages/urwid/raw_display.py", line 393, in <lambda>
    event_loop, callback, self.get_available_raw_input())
  File "/usr/local/lib/python3.5/dist-packages/urwid/raw_display.py", line 493, in parse_input
    callback(processed, processed_codes)
  File "/usr/local/lib/python3.5/dist-packages/urwid/main_loop.py", line 403, in _update
    self.process_input(keys)
  File "/usr/local/lib/python3.5/dist-packages/urwid/main_loop.py", line 503, in process_input
    k = self._topmost_widget.keypress(self.screen_size, k)
  File "/media/sf_git/mitmproxy/mitmproxy/console/window.py", line 42, in keypress
    k = super(self.__class__, self).keypress(size, k)
  File "/usr/local/lib/python3.5/dist-packages/urwid/container.py", line 1116, in keypress
    return self.footer.keypress((maxcol,),key)
  File "/media/sf_git/mitmproxy/mitmproxy/console/statusbar.py", line 134, in keypress
    return self.master.ab.keypress(*args, **kwargs)
  File "/media/sf_git/mitmproxy/mitmproxy/console/statusbar.py", line 89, in keypress
    self.prompt_execute(self._w.get_edit_text())
  File "/media/sf_git/mitmproxy/mitmproxy/console/statusbar.py", line 112, in prompt_execute
    msg = p(txt, *args)
  File "/media/sf_git/mitmproxy/mitmproxy/console/master.py", line 319, in run_script_once
    except script.ScriptException as e:
AttributeError: module 'mitmproxy.script' has no attribute 'ScriptException'

---

Mitmproxy Version: master
Operating System: Ubuntu 14.04 x64

[dufferzafar]

The main reason this is happening is because mitmproxy.script should now be mitmproxy.builtins.script due to changes made in #1356