* improved detection of inside-project environments
* make list command faster (by only instantiating the spider manger)
* print a warning when extensions (middlewares, etc) are disabled with a message on NotConfigured exception
* assert that scrapy configuration hasn't been loaded in scrapyd.runner
* simplified IgnoreRequest exception, to avoid loading settings when importing scrapy.exceptions
* added test to make sure certain modules don't cause scrapy.conf module to be
loaded, to ensure the scrapyd runner bootstraping performs properly
