Fix IntelliJ compilation level

Keep getting

Warning:java: source value 1.5 is obsolete and will be removed in a future release
Warning:java: To suppress warnings about obsolete options, use -Xlint:-options.

If still no luck with changing the settings below...

Try add the following to pom.xml

 <build>  
     <plugins>  
       <plugin>  
         <groupId>org.apache.maven.plugins</groupId>  
         <artifactId>maven-compiler-plugin</artifactId>  
         <version>3.1</version>  
         <configuration>  
           <source>1.8</source>  
           <target>1.8</target>  
         </configuration>  
       </plugin>  
     </plugins>  
   </build>