New core middleware, MIME.

And added tests for status code and scheme

Turns out the stuff in the test file needs to be exported so external add-ons can use them

fastcgi: Stripping PATH_INFO from SCRIPT_NAME

Conflicts:
	middleware/fastcgi/fastcgi.go

core: change to new http2 repo

The golang.org/x/net/http2 is now the official http2 repo.
It is advised to change the imports to it.

Also updated change list and added/improved tests

rewrite: Use middleware.Replacer

Bug fix for regexps starting with '/'.

browse: User defined variables (for templates)

Update

browse: Option to ignore indexes

Use latest Go minor versions for testing

Signed-off-by: Alexander Morozov <lk4d4@docker.com>

markdown: Use less strict condition to avoid problems with concurrency

In latest go versions TestWatcher fails pretty often, because it is
"more concurrent" now. Reproducible with go master:
while go test github.com/mholt/caddy/middleware/markdown; do :; done
Signed-off-by: Alexander Morozov <lk4d4@docker.com>

Fix all vet warnings and add vet check to CI

markdown: fix race in accessing map