With must be called on log.filter, otherwise "main" entries get filtered

Also, we should allow "main" module to log INFO messages like

```
I[02-07|07:57:25.074] Found private validator                      module=main path=/home/vagrant/.tendermint/config/priv_validator.json
I[02-07|07:57:25.076] Found genesis file                           module=main path=/home/vagrant/.tendermint/config/genesis.json
```

Refs https://github.com/cosmos/gaia/issues/118

**BEFORE**:
```
$ tendermint init

```

**AFTER**:
```
$ tendermint init
I[02-07|07:57:25.074] Found private validator                      module=main path=/home/vagrant/.tendermint/config/priv_validator.json
I[02-07|07:57:25.076] Found genesis file                           module=main path=/home/vagrant/.tendermint/config/genesis.json
```

cmd/tendermint/commands/root.go

@@ -14,7 +14,7 @@ import (
 
 var (
 	config = cfg.DefaultConfig()
-	logger = log.NewTMLogger(log.NewSyncWriter(os.Stdout)).With("module", "main")
+	logger = log.NewTMLogger(log.NewSyncWriter(os.Stdout))
 )
 
 func init() {
@@ -57,6 +57,7 @@ var RootCmd = &cobra.Command{
 		if viper.GetBool(cli.TraceFlag) {
 			logger = log.NewTracingLogger(logger)
 		}
+		logger = logger.With("module", "main")
 		return nil
 	},
 }

config/config.go

@@ -189,9 +189,10 @@ func DefaultLogLevel() string {
 	return "error"
 }
 
-// DefaultPackageLogLevels returns a default log level setting so all packages log at "error", while the `state` package logs at "info"
+// DefaultPackageLogLevels returns a default log level setting so all packages
+// log at "error", while the `state` and `main` packages log at "info"
 func DefaultPackageLogLevels() string {
-	return fmt.Sprintf("state:info,*:%s", DefaultLogLevel())
+	return fmt.Sprintf("main:info,state:info,*:%s", DefaultLogLevel())
 }
 
 //-----------------------------------------------------------------------------