Add versioning to perf SQL database

perf/go/trybot/trybot.go

 /** trybot is for loading and serving trybot performance results.
 
   Implementation notes:
 
     Regular files are in:
 
     gs://chromium-skia-gm/nano-json-v1/2014/08/07/01/Perf-...-Release/nanobench_da7a94...8d35a_1407357280.json
 
     while trybots are in:
 
@@ skipping 155 matching lines @@
         ResultsFileLocation *ingester.ResultsFileLocation
         IssueName           string
 }
 
 type BenchByIssueSlice []*BenchByIssue
 
 func (p BenchByIssueSlice) Len() int           { return len(p) }
 func (p BenchByIssueSlice) Less(i, j int) bool { return p[i].IssueName < p[j].IssueName }
 func (p BenchByIssueSlice) Swap(i, j int)      { p[i], p[j] = p[j], p[i] }
 
-func Init() {
-        db.Init()
+func init() {
         var err error
         st, err = storage.New(util.NewTimeoutClient())
         if err != nil {
                 panic("Can't construct HTTP client")
         }
         elapsedTimePerUpdate = metrics.NewRegisteredTimer("ingester.trybot.nano.update", metrics.DefaultRegistry)
         metricsProcessed = metrics.NewRegisteredCounter("ingester.trybot.nano.processed", metrics.DefaultRegistry)
         numSuccessUpdates = metrics.NewRegisteredCounter("ingester.trybot.nano.updates", metrics.DefaultRegistry)
 }
 
@@ skipping 42 matching lines @@
                         return fmt.Errorf("Update failed to write trybot results: %s", err)
                 }
         }
 
         numSuccessUpdates.Inc(1)
         elapsedTimePerUpdate.UpdateSince(begin)
         glog.Infof("Finished trybot ingestion.")
 
         return nil
 }