Support ad-hoc keep-alive for HTTP/1.0 Clients

Only go for keep-alive if they submit a 'connection: keep-alive' header
in the request, keep behaviour the same otherwise.

The new RFC 7230 (http://tools.ietf.org/html/rfc7230#section-6.3)
states:

    If the received protocol is HTTP/1.0, the "keep-alive" connection
    option is present, the recipient is not a proxy, and the recipient
    wishes to honor the HTTP/1.0 "keep-alive" mechanism, the
    connection will persist after the current response;

Even though clients are discouraged from doing so in Appendix A.1.2
(http://tools.ietf.org/html/rfc7230#appendix-A.1.2)
Merge branch 'http-1-0-keepalive' of git://github.com/heroku/cowboy
fix a documentation typo

The function `set_resp_header' is defined in `cowboy_req'
module, not the `cowboy'.
Merge branch 'master' of git://github.com/ztmr/cowboy
Update to erlang.mk 1.0.0
Update the Getting started chapter to new erlang.mk

Length of the chapter divided by 2! \o/
Add OTP release support and versioning info to the guide
Update AUTHORS
Update rebar.config
Update CHANGELOG
Remove 1.0 section in the ROADMAP
Update Cowboy to 1.0.0
Fix bad link format in the guide
Update links extend -> ninenines
Fix language in getting started
Accept absolute URI scheme as uppercase

We should be doing a case insensitive comparison to be correct,
but this is more expensive. Almost all clients send lowercase,
this patch fixes handling of the aws/aws-sdk-php client which
sends uppercase, and no known client sends mixed case so I am
holding back on the more expensive solution for the moment.
Handle absolute URIs that lack a path entirely
Fix REST guide reference to accept_missing_post

The guide refers to accept_missing_post instead of allow_missing_post.
Merge branch 'patch-1' of git://github.com/asabil/cowboy
Add cowboy_req:part/2 export