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

* introduced own ChallengeProvider type, based on acme.ChallengeProvider to avoid vendoring/version mismatches in Caddy plugins; see Caddy issue #1697

* fixed up comments for ChallengeProvider

* moved ChallengeProvider to caddytls/tls.go

Update Initscripts

"$(which caddy)" is not work at startup. 
After this change, I can run "insserv -d caddy" to start caddy automatically on boot.

* Update plugins.go

* Add extraInfo to eventHook

* Add extraInfo to eventHook

* Update run.go

* Update run.go

* Update run.go

Related to #1660 and #1667

* Browse: Show symbolic links and targets type properly
 * gofmt
Signed-off-by: Jonas Östanbäck <jonas.ostanback@gmail.com>

* Move symbolic link check in to isSymlinkTargetDir
Signed-off-by: Jonas Östanbäck <jonas.ostanback@gmail.com>

* Revert template change and show sym link folders as normal folders

* browse: Updated icons including symlink indicators

* Add grpc plugin directive

* Update plugin.go

Removed whitespace line

* Update plugin.go

Vendor all dependencies

The vendor/ folder was created with the help of @FiloSottile's gvt and
vendorcheck.

Any dependencies of Caddy plugins outside this repo are not vendored.

We do not remove any unused, vendored packages because vendorcheck -u
only checks using the current build configuration; i.e. packages that
may be imported by files toggled by build tags of other systems.

CI tests have been updated to ignore the vendor/ folder. When Go 1.9 is
released, a few of the go commands should be revised to again use ./...
as it will ignore the vendor folder by default.