browse: allow consecutive spaces in filenames

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