opentracing -> opencensus (#802)

* update vendor directory, add go.opencensus.io

* update imports

* oops

* s/opentracing/opencensus/ & remove prometheus / zipkin stuff & remove old stats

* the dep train rides again

* fix gin build

* deps from last guy

* start in on the agent metrics

* she builds

* remove tags for now, cardinality error is fussing. subscribe instead of register

* update to patched version of opencensus to proceed for now TODO switch to a release

* meh

fix imports

* println debug the bad boys

* lace it with the tags

* update deps again

* fix all inconsistent cardinality errors

* add our own logger

* fix init

* fix oom measure

* remove bugged removal code

* fix s3 measures

* fix prom handler nil

vendor/github.com/containerd/continuity/fs/diff_windows.go

@@ -0,0 +1,32 @@
+package fs
+
+import (
+	"os"
+
+	"golang.org/x/sys/windows"
+)
+
+func detectDirDiff(upper, lower string) *diffDirOptions {
+	return nil
+}
+
+func compareSysStat(s1, s2 interface{}) (bool, error) {
+	f1, ok := s1.(windows.Win32FileAttributeData)
+	if !ok {
+		return false, nil
+	}
+	f2, ok := s2.(windows.Win32FileAttributeData)
+	if !ok {
+		return false, nil
+	}
+	return f1.FileAttributes == f2.FileAttributes, nil
+}
+
+func compareCapabilities(p1, p2 string) (bool, error) {
+	// TODO: Use windows equivalent
+	return true, nil
+}
+
+func isLinked(os.FileInfo) bool {
+	return false
+}