Allow dots in args names

[ivanprado]

I have a spider with a dot in arg names (e.g. -a discovery_tasks.1.url=http://example.com). I can run it without problems in Scrapy and in Scrapy Cloud if I set the arguments manually, but I cannot schedule it using shub:

Error: discovery_tasks.1.url: Only letters, digits and _ allowed in args names.

It would be nice to allow also dots in args in shub.