use requests instead of willie's web library for SNI support

without requests, https://blog.matan.me/ would return an SSL
verification error:

ssl.CertificateError: hostname 'blog.matan.me' doesn't match either of 'ssl2000.cloudflare.com', 'cloudflare.com', '*.cloudflare.com' (file "/usr/lib/python3.4/ssl.py", line 284, in match_hostname)

I had expected python3 to support SNI, but it doesn't seem to be the
case.

you can also compare the output of:

    gnutls-cli blog.matan.me
    gnutls-cli --disable-sni blog.matan.me

...to reproduce the "non-SNI" problem from gnutls-cli.