remove QuoteCharacter option

This seems to be one of the most reported issues, as it makes it a lot
harder to safely escape strings.

This option is very much an edge case, and it's causing too much issues
compared to what it provide.

text_formatter.go

@@ -52,10 +52,6 @@ type TextFormatter struct {
 	// QuoteEmptyFields will wrap empty fields in quotes if true
 	QuoteEmptyFields bool
 
-	// QuoteCharacter can be set to the override the default quoting character "
-	// with something else. For example: ', or `.
-	QuoteCharacter string
-
 	// Whether the logger's out is to a terminal
 	isTerminal bool
 
@@ -63,9 +59,6 @@ type TextFormatter struct {
 }
 
 func (f *TextFormatter) init(entry *Entry) {
-	if len(f.QuoteCharacter) == 0 {
-		f.QuoteCharacter = "\""
-	}
 	if entry.Logger != nil {
 		f.isTerminal = IsTerminal(entry.Logger.Out)
 	}
@@ -177,13 +170,6 @@ func (f *TextFormatter) appendValue(b *bytes.Buffer, value interface{}) {
 	if !f.needsQuoting(stringVal) {
 		b.WriteString(stringVal)
 	} else {
-		b.WriteString(f.quoteString(stringVal))
+		b.WriteString(fmt.Sprintf("%q", stringVal))
 	}
 }
-
-func (f *TextFormatter) quoteString(v string) string {
-	escapedQuote := fmt.Sprintf("\\%s", f.QuoteCharacter)
-	escapedValue := strings.Replace(v, f.QuoteCharacter, escapedQuote, -1)
-
-	return fmt.Sprintf("%s%v%s", f.QuoteCharacter, escapedValue, f.QuoteCharacter)
-}