* Adding nobots directive

* Moving nobots directive behind log one.

* Move nobots directive to a better position

gzip: change ETag to weak etag after gzip

According to https://tools.ietf.org/html/rfc7232#section-2.1
> Likewise, a validator is weak if it is shared by two or more
representations of a given resource at the same time, unless those
representations have identical representation data.  For example, if
the origin server sends the same validator for a representation with
a gzip content coding applied as it does for a representation with no
content coding, then that validator is weak.

Therefore, after gzip, we should change the original etag to weak etag.

Not much changed but it's a clean pull now; easier for future reference.

* uses more of the builtin functionality for starting and stopping of the process by using command and command_args along with procname
* removed -f from daemon as this was hiding error message that were sent to stdout on startup, now writing stdout to the logfile directly

for example, this was being hidden:

“Activating privacy features.. [www.domain.com] failed to get certificate: Error presenting token: Could not find the start of authority”

it now shows up in the log

* aded “caddy_env” to allow the setting of environment variables that caddy might need, for example when setting creds for “DNS Challenge”

* added a check to ensure caddy_config_path file exists

* rename requestid request_id

* rename folder

* folder name match package name requestid

proxy: add Header load balancing policy

gzip,mime: show response header instead of the request one in test message

adds unix timestamp placeholder

proxy: Fix CI fail from format token in Error call

go vet caused a build fail in https://travis-ci.org/mholt/caddy/jobs/248392875:
   upstream_test.go:480::error: possible formatting directive in Error call (vet)

This patch changes the Error call added in commit 078c9915 to
an Errorf call to support the use of the %d token.

markdown: fix the real ineffectual assignments in test

Signed-off-by: Tw <tw19881113@gmail.com>

* vendor: update Lumberjack dep

* httpserver/roller: introduce rotate_compress directive

This directive will enable gzip compression provided by [Lumberjack](https://github.com/natefinch/lumberjack/pull/43).

The directive `rotate_compress` can be `true` or `false`, being `false` by default.

* httpserver/roller: remove need to set bool with rotate_compress option

markdown: reload template on each request and fix fake tests

Signed-off-by: Tw <tw19881113@gmail.com>

See discussion on commit c9b022b5

If we overwrite the Server header, it becomes difficult/impossible to
know from the client whether the request was proxied through Caddy.

Signed-off-by: Tw <tw19881113@gmail.com>

Signed-off-by: Tw <tw19881113@gmail.com>

* Create request_id directive #1590

* Address Comments

* Fix TestListenerAddrEqual

* requestid: Add some tests

* Address Comments by tobya

* Address Comments