Add codacy grade bage

Author: flexferrum

README.md

@@ -5,6 +5,7 @@
 [![Build Status](https://travis-ci.org/flexferrum/Jinja2Cpp.svg?branch=master)](https://travis-ci.org/flexferrum/Jinja2Cpp)
 [![Build status](https://ci.appveyor.com/api/projects/status/19v2k3bl63jxl42f/branch/master?svg=true)](https://ci.appveyor.com/project/flexferrum/Jinja2Cpp)
 [![Coverage Status](https://codecov.io/gh/flexferrum/Jinja2Cpp/branch/master/graph/badge.svg)](https://codecov.io/gh/flexferrum/Jinja2Cpp)
+[![Codacy Badge](https://api.codacy.com/project/badge/Grade/d932d23e9288404ba44a1f500ab42778)](https://www.codacy.com/app/flexferrum/Jinja2Cpp?utm_source=github.com&utm_medium=referral&utm_content=flexferrum/Jinja2Cpp&utm_campaign=Badge_Grade)
 [![Github Releases](https://img.shields.io/github/release/flexferrum/Jinja2Cpp.svg)](https://github.com/flexferrum/Jinja2Cpp/releases)
 [![Github Issues](https://img.shields.io/github/issues/flexferrum/Jinja2Cpp.svg)](http://github.com/flexferrum/Jinja2Cpp/issues)
 [![GitHub License](https://img.shields.io/badge/license-Mozilla-blue.svg)](https://raw.githubusercontent.com/flexferrum/Jinja2Cpp/master/LICENSE)