Enhance config restore to carry previous set content as well (#8483)

This PR brings support for `history` list to
list in the following agreed format

```
~ mc admin config history list -n 2 myminio
RestoreId: df0ebb1e-69b0-4043-b9dd-ab54508f2897
Date: Mon, 04 Nov 2019 17:27:27 GMT

region name="us-east-1" state="on"
region name="us-east-1" state="on"
region name="us-east-1" state="on"
region name="us-east-1" state="on"

RestoreId: ecc6873a-0ed3-41f9-b03e-a2a1bab48b5f
Date: Mon, 04 Nov 2019 17:28:23 GMT

region name=us-east-1 state=off
```

This PR also moves the help templating and coloring to
fully `mc` side instead than `madmin` API.

pkg/madmin/parse-kv.go

@@ -88,11 +88,11 @@ const (
 	KvSeparator        = `=`
 	KvSpaceSeparator   = ` `
 	KvComment          = `#`
+	KvNewline          = "\n"
 	KvDoubleQuote      = `"`
 	KvSingleQuote      = `'`
 
-	KvNewline = "\n"
-	Default   = `_`
+	Default = `_`
 )
 
 // This function is needed, to trim off single or double quotes, creeping into the values.
@@ -140,8 +140,8 @@ func convertTargets(s string, targets Targets) error {
 	return nil
 }
 
-// parseSubSysTarget - parse sub-system target
-func parseSubSysTarget(buf []byte) (Targets, error) {
+// ParseSubSysTarget - parse sub-system target
+func ParseSubSysTarget(buf []byte) (Targets, error) {
 	targets := make(map[string]map[string]KVS)
 	bio := bufio.NewScanner(bytes.NewReader(buf))
 	for bio.Scan() {