Use plain socket objects instead of wrapper classes

[tilgovi]

Refactor socket creation to remove the socket wrapper classes so that these objects have less surprising behavior when used in worker hooks, worker classes, and custom applications.

Close #3013.

[jsprieto10]

is there anything else missing for this?

[tilgovi]

@benoitc polite bump, if you have the time

[benoitc]

@tilgovi is this ready for review or do yui think to any other addition/changes already?

[tnusser]

@tilgovi What is the status of your PR?

[pajod]

Should the monkey patching in gunicorn/workers/ggevent.py stay the same?

I was able to run my WIP request after reloading test against your PR after fixing just the following variable access:

- sockets.append(socket.socket(s.FAMILY, socket.SOCK_STREAM,
-                                          fileno=s.sock.fileno()))
+ sockets.append(socket.socket(s.family, socket.SOCK_STREAM,
+                                          fileno=s.fileno()))

EDIT: rebased a24ff07d3cf899b3fd05287d34ba145e85cbbd80 - including the above fix here: https://github.com/benoitc/gunicorn/compare/master...pajod:gunicorn:patch-plain-socket