Make verify_hostname take an OpenSSL connection

This is related to issue #1 that indicates that we may need more power to
verify everything we need in the future.

This is grossly backward-incompatible but service_identity is pre-alpha for
exactly these cases.
Merge pull request #2 from glyph/master

It's ``nameConstraints`` not "name constrains"
Better docstring for verify_hostname
Credit @glyph
Grammar
Refactor service_identity into a package

Most notably, pyOpenSSL specific code lives in service_identity.pyopenssl now.
Release 0.2
Fix outdate docstring for verify_service_identity
Start 0.3 cycle
Travis supports 3.4 now
Fix for idna 0.6
Document that idna 0.6 is required
Add changelog entry
Kill off _attrs and port to characteristic