Support requests>=2.14.0
Support requests>=2.14.0

From that release onwards, `cert_verify` raises `IOError` [1].

    1: https://github.com/kennethreitz/requests/commit/7d8b87c

PKRoma/httpie,jkbrzt/httpie,jakubroztocil/httpie,jkbrzt/httpie,PKRoma/httpie,jakubroztocil/httpie,jakubroztocil/httpie,jkbrzt/httpie