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/stat_linux.go

@@ -0,0 +1,27 @@
+package fs
+
+import (
+	"syscall"
+	"time"
+)
+
+// StatAtime returns the Atim
+func StatAtime(st *syscall.Stat_t) syscall.Timespec {
+	return st.Atim
+}
+
+// StatCtime returns the Ctim
+func StatCtime(st *syscall.Stat_t) syscall.Timespec {
+	return st.Ctim
+}
+
+// StatMtime returns the Mtim
+func StatMtime(st *syscall.Stat_t) syscall.Timespec {
+	return st.Mtim
+}
+
+// StatATimeAsTime returns st.Atim as a time.Time
+func StatATimeAsTime(st *syscall.Stat_t) time.Time {
+	// The int64 conversions ensure the line compiles for 32-bit systems as well.
+	return time.Unix(int64(st.Atim.Sec), int64(st.Atim.Nsec)) // nolint: unconvert
+}