Как использовать pip для установки промежуточного ПО на Scrapinghub

У меня есть проект scrapy, который использует установку промежуточного программного обеспечения через pip. В частности, scrapy-random-useragent.

Установка файла # -- кодировка: utf-8 --

# Scrapy settings for batdongsan project
#
# For simplicity, this file contains only settings considered important or
# commonly used. You can find more settings consulting the documentation:
#
#     http://doc.scrapy.org/en/latest/topics/settings.html
#     http://scrapy.readthedocs.org/en/latest/topics/downloader-middleware.html
#     http://scrapy.readthedocs.org/en/latest/topics/spider-middleware.html

BOT_NAME = 'batdongsan'

SPIDER_MODULES = ['batdongsan.spiders']
NEWSPIDER_MODULE = 'batdongsan.spiders'
FEED_EXPORT_ENCODING = 'utf-8' # make output in json become human readable utf-8
CLOSESPIDER_PAGECOUNT = 10 # limit the number of page crawl
LOG_LEVEL = 'INFO' # write less log

# Obey robots.txt rules
ROBOTSTXT_OBEY = True

# Enable or disable downloader middlewares
# See http://scrapy.readthedocs.org/en/latest/topics/downloader-middleware.html
DOWNLOADER_MIDDLEWARES = {
    #'batdongsan.middlewares.MyCustomDownloaderMiddleware': 543,
    'scrapy.contrib.downloadermiddleware.useragent.UserAgentMiddleware': None,
    'random_useragent.RandomUserAgentMiddleware': 400
}
USER_AGENT_LIST = "agents.txt"

Проект scrapy отлично работает на моей машине.
Я выполняю развертывание на scrapinghub, используя связанный проект github.
Я получил ошибку в журналах на scrapinghub.

  File "/usr/local/lib/python2.7/site-packages/scrapy/commands/crawl.py", line 57, in run
    self.crawler_process.crawl(spname, **opts.spargs)
  File "/usr/local/lib/python2.7/site-packages/scrapy/crawler.py", line 168, in crawl
    return self._crawl(crawler, *args, **kwargs)
  File "/usr/local/lib/python2.7/site-packages/scrapy/crawler.py", line 172, in _crawl
    d = crawler.crawl(*args, **kwargs)
  File "/usr/local/lib/python2.7/site-packages/twisted/internet/defer.py", line 1445, in unwindGenerator
    return _inlineCallbacks(None, gen, Deferred())
--- <exception caught here> ---
  File "/usr/local/lib/python2.7/site-packages/twisted/internet/defer.py", line 1299, in _inlineCallbacks
    result = g.send(result)
  File "/usr/local/lib/python2.7/site-packages/scrapy/crawler.py", line 95, in crawl
    six.reraise(*exc_info)
  File "/usr/local/lib/python2.7/site-packages/scrapy/crawler.py", line 77, in crawl
    self.engine = self._create_engine()
  File "/usr/local/lib/python2.7/site-packages/scrapy/crawler.py", line 102, in _create_engine
    return ExecutionEngine(self, lambda _: self.stop())
  File "/usr/local/lib/python2.7/site-packages/scrapy/core/engine.py", line 69, in __init__
    self.downloader = downloader_cls(crawler)
  File "/usr/local/lib/python2.7/site-packages/scrapy/core/downloader/__init__.py", line 88, in __init__
    self.middleware = DownloaderMiddlewareManager.from_crawler(crawler)
  File "/usr/local/lib/python2.7/site-packages/scrapy/middleware.py", line 58, in from_crawler
    return cls.from_settings(crawler.settings, crawler)
  File "/usr/local/lib/python2.7/site-packages/scrapy/middleware.py", line 34, in from_settings
    mwcls = load_object(clspath)
  File "/usr/local/lib/python2.7/site-packages/scrapy/utils/misc.py", line 44, in load_object
    mod = import_module(module)
  File "/usr/local/lib/python2.7/importlib/__init__.py", line 37, in import_module
    __import__(name)
exceptions.ImportError: No module named random_useragent

понятно, что проблема No module named random_useragent.

Но я не знаю, как установить этот модуль через pip на Scrapinghub.