[READY] Improve socket completion on Python 2

[micbou]

See discussion in https://github.com/Valloric/YouCompleteMe/issues/2562.

One downside of adding a module to the auto_import_modules setting is that it makes the module as a built in one and so it cannot be jumped to. I think proper completions outweigh the ability to jump (I rarely want to jump into a module of the standard library) but you may disagree.

---

This change is 

[vheon]

but you may disagree.

I don't :smiley:

@homu r+

---

Reviewed 4 of 4 files at r1. Review status: all files reviewed at latest revision, all discussions resolved.

---

Comments from Reviewable

[homu]

:pushpin: Commit 200e330 has been approved by vheon

[homu]

:zap: Test exempted - status