Add Javadoc badge with automatic version detection (togglz#160)

README.md

@@ -1,7 +1,8 @@
 # Togglz
 [![Gitter](https://badges.gitter.im/togglz/togglz.svg)](https://gitter.im/togglz/togglz)
 [![Build Status](https://travis-ci.org/togglz/togglz.svg?branch=master)](https://travis-ci.org/togglz/togglz)
-[![Maven Central](https://img.shields.io/maven-central/v/org.togglz/togglz-core.svg)]()
+[![Maven Central](https://img.shields.io/maven-central/v/org.togglz/togglz-core.svg)](https://maven-badges.herokuapp.com/maven-central/org.togglz/togglz-core)
+[![Javadoc](https://javadoc-emblem.rhcloud.com/doc/org.togglz/togglz-core/badge.svg?prefix=v&color=blue)](http://www.javadoc.io/doc/org.togglz/togglz-core)
 
  Togglz is an implementation of the Feature Toggles pattern for Java. Feature Toggles are a very common agile development practices in the context of continuous deployment and delivery. The basic idea is to associate a toggle with each new feature you are working on. This allows you to enable or disable these features at application runtime, even for individual users.