Update maven groupID and README

Author: stevenlagoy

README.md

@@ -17,7 +17,7 @@ Add this dependency to your `pom.xml`:
 
 ```xml
 <dependency>
-    <groupId>com.example</groupId>
+    <groupId>com.github.stevenlagoy</groupId>
     <artifactId>json-java-objectifier</artifactId>
     <version>1.0.0</version>
 </dependency>

pom.xml

@@ -2,7 +2,7 @@
          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
          xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>
-    <groupId>com.example</groupId>
+    <groupId>com.github.stevenlagot</groupId>
     <artifactId>json-java-objectifier</artifactId>
     <version>1.0.0</version>
     <packaging>jar</packaging>