Change [tags] to [global_tags] to deal with toml bug

closes #662

internal/config/config.go

@@ -138,7 +138,7 @@ var header = `# Telegraf configuration
 # file would generate.
 
 # Global tags can be specified here in key="value" format.
-[tags]
+[global_tags]
   # dc = "us-east-1" # will tag all metrics with dc=us-east-1
   # rack = "1a"
 
@@ -333,9 +333,9 @@ func (c *Config) LoadConfig(path string) error {
 				log.Printf("Could not parse [agent] config\n")
 				return err
 			}
-		case "tags":
+		case "global_tags", "tags":
 			if err = config.UnmarshalTable(subTable, c.Tags); err != nil {
-				log.Printf("Could not parse [tags] config\n")
+				log.Printf("Could not parse [global_tags] config\n")
 				return err
 			}
 		case "outputs":

internal/config/testdata/telegraf-agent.toml

@@ -20,7 +20,7 @@
 # with 'required'. Be sure to edit those to make this configuration work.
 
 # Tags can also be specified via a normal map, but only one form at a time:
-[tags]
+[global_tags]
   dc = "us-east-1"
 
 # Configuration for telegraf agent