feat: able to customize home page now (#24)

model/option.go

@@ -39,6 +39,7 @@ func InitOptionMap() {
 	common.OptionMap["SMTPToken"] = ""
 	common.OptionMap["Notice"] = ""
 	common.OptionMap["About"] = ""
+	common.OptionMap["HomePageContent"] = ""
 	common.OptionMap["Footer"] = common.Footer
 	common.OptionMap["ServerAddress"] = ""
 	common.OptionMap["GitHubClientId"] = ""