Convert our HTTP requests from urllib2 to requests.
Review Request #2863 — Created Feb. 12, 2012 and submitted
Convert our HTTP requests from urllib2 to requests. In addition to being a downright awful API to use, urllib2 has a fundamental flaw in that it will only send HTTP Basic Auth information if the first request for the resource comes back with a www-authenticate header. This doesn't work for many HTTPS mercurial repositories, and it doesn't work with some 3rd-party providers of raw-file URLs like Codebase HQ's API. This change converts our code to use the 'requests' module, which is downright sexy. 'requests' will also do a much better job of trying to guess the charset of any text we get.
Ran unit tests, tested repository connectivity to an HTTPS Mercurial repository which required authentication.