Proxyaddr fix

[goodboy]

Redo of #35.
Fixes #36 and hopefully #39.

@y-luis @access2praveen mind having a quick look / trying this out.

[y-luis-rojo]

@tgoodlet, tested OK from my side 👍

[goodboy]

Huh, interesting pypy failures. I'll have to check that out manually.

[luismartingil]

@goodboy Can we maybe use pluggy-0.11.0? Looks like it does the trick (python 2.7):

platform linux2 -- Python 2.7.5, pytest-4.5.0, py-1.8.0, pluggy-0.11.0
rootdir: /Volumes/data/pysipp
collected 55 items

tests/test_agent.py ...........                                                                                                                                                                              [ 20%]
tests/test_commands.py .....                                                                                                                                                                                 [ 29%]
tests/test_launcher.py ..                                                                                                                                                                                    [ 32%]
tests/test_loader.py ..                                                                                                                                                                                      [ 36%]
tests/test_stack.py ...................................

[goodboy]

Huh very good point @luismartingil.
Just pushed a commit to use latest pluggy.

[goodboy]

Hmm seems to still be failing @luismartingil even with pluggy==0.11.0. I don't have pypy set up locally atm. Did you actually test with the version that's running on travis?

[goodboy]

Dropped pypy in CI as per #52 and #51 to get this moving!