Refactor logging to remove logger, use fluentd with kubernetes filter (#380)

Remove the `logger` container from the logging daemonset. 

Remove the outgoing call from the poolmgr to the logger.  Use Fluentd's Kubernetes filter to add function name and UID to influx metadata.  

This means fluentd now figures out when to start collecting function logs on its own, without being informed by poolmgr.  This is great for other execution strategies, and for autoscaling, where fission isn't in direct control of function pod creation.

Also adds an integration test to make sure logging keeps working.

fission/logdb/influxdb.go

@@ -96,14 +96,15 @@ func (influx InfluxDB) GetLogs(filter LogFilter) ([]LogEntry, error) {
 					log.Fatal(err)
 				}
 				logEntries = append(logEntries, LogEntry{
+					//The attributes of the LogEntry are selected as relative to their position in InfluxDB's line protocol response
 					Timestamp: t,
-					Container: row[2].(string),
-					FuncName:  row[3].(string),
-					FuncUid:   row[4].(string),
-					Message:   strings.TrimSuffix(row[5].(string), "\n"),
-					Namespace: row[6].(string),
-					Pod:       row[7].(string),
-					Stream:    row[8].(string),
+					Container: row[2].(string),                            //docker_container_id
+					FuncName:  row[8].(string),                            //kubernetes_labels_functionName
+					FuncUid:   row[3].(string),                            //funcuid
+					Message:   strings.TrimSuffix(row[17].(string), "\n"), //log field
+					Namespace: row[14].(string),                           //kubernetes_namespace_name
+					Pod:       row[15].(string),                           //kubernetes_pod_name
+					Stream:    row[18].(string),                           //stream
 				})
 			}
 		}