fixed plugin version warning

#63

Author: nmcl

pom.xml

@@ -6,13 +6,18 @@
   <name>javasim</name>
   <version>2.1</version>
   <url>http://maven.apache.org</url>
+  <properties>
+    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+  </properties>
   <build>
     <plugins>
       <plugin>
         <artifactId>maven-compiler-plugin</artifactId>
-        <configuration> 
-          <source>1.6</source>
-          <target>1.6</target>
+	<groupId>org.apache.maven.plugins</groupId>
+	<version>3.6.0</version>
+        <configuration>
+          <source>1.8</source>
+          <target>1.8</target>
         </configuration>
       </plugin>
     </plugins>