letsencrypt: Fix perm of user key

gzip: Add .svg to default ext list

Also only set custom address if alternate port is specified (rather than using a blank address; just cleaner this way)

gzip: Fix for wrong content-type when templates is used.

This change fixes the scenario where you reload the config and it tries to obtain a cert from the ACME server, but no email address is found or terms have not been agreed to in-process. This is unfortunate but it should not stop the server from reloading, so we assume empty email address in this case.

This prevents serving HTTPS over port 80 or HTTP over 443. It's confusing and we don't allow it.

It is unexpected to serve localhost on port 443 or any server on 443 if TLS is disabled, even if the port is blank. Also don't warn about how to force TLS on the HTTP port.

The docs link to this structure and all its methods related to the browse template; keeping them together makes it possible to link to the whole block of code that is relevant.

Doesn't test the SkipInsecureVerify proxy setting, but that can be done at another time.

# Conflicts:
#	caddy/letsencrypt/letsencrypt.go
#	caddy/letsencrypt/letsencrypt_test.go

Also make sure column header cells don't wrap

rewrite: not_has, not_match, multiple to, and status codes

letsencrypt: Make plaintext redirect hosts honor the Bind settings

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".