Makes restarts cleaner and improves configuration usability related to the tls directive

# Conflicts:
#	caddy/letsencrypt/letsencrypt.go

Before, Caddy couldn't support graceful (zero-downtime) restarts when the reloaded Caddyfile had a host in it that was elligible for a LE certificate because the port was already in use. This commit makes it possible to do zero-downtime reloads and issue certificates for new hosts that need it. Supports only http-01 challenge at this time.

OCSP stapling is improved in that it updates before the expiration time when the validity window has shifted forward. See 30c94908. Before it only used to update when the status changed.

This commit also sets the user agent for Let's Encrypt requests with a string containing "Caddy".

By separating scheme and port at the parser, we are able to set the port appropriately and also keep the semantics of the scheme being specified by the user later on. The parser also stores an address' original input. Also, the config refactor makes it possible to partially load a config - valuable for determining which ones will need Let's Encrypt integration turned on during a restart.

rewrite: Support for rewrite match group.

Replacer patch

Rewrite improvements

Support glob character in import

markdown: Fix panic on sitegen for request dependent template values.

Gzip: Fix missing gzip encoding headers.

Gzip: Append to Vary header instead of replacing.

fastcgi: Close client connections when done.

tls: Remove ECDHE-RSA-3DES-EDE-CBC-SHA and RSA-3DES-EDE-CBC-SHA from the default TLS config

Feek --> Feel

unless you meant Freak