Resolve "Gitlab daemon crashing. Omnibus installation (Ubuntu 14.04)"

This MR fixes a collection of small problems thrown up while investigating the named issue:

• Some error messages are not reported correctly due to using println instead of log.Println
• Exercise the chrooted mode in the acceptance tests
• Document the CGO_ENABLED=0 requirement of the chrooted mode
• Clean up acceptance test running a little
• Add Go 1.8 to the list of CI builds
• Run the acceptance tests on all CI builds

Closes #4 (closed)

Makefile

@@ -40,10 +40,11 @@ complexity:
 test:
 	go get golang.org/x/tools/cmd/cover
-	go test ./... -cover -v -timeout 1m
+	go test ./... -short -cover -v -timeout 1m
 acceptance: gitlab-pages
-	go test ./... -run-acceptance-tests -v -timeout 1m
+	go get golang.org/x/tools/cmd/cover
+	go test ./... -cover -v -timeout 1m
 docker:
 	docker run --rm -it -v ${PWD}:/go/src/pages -w /go/src/pages golang:1.5 /bin/bash