added IDEA project files to gitignore, set Maven java version to 8

Java/.gitignore

@@ -1 +1,5 @@
-*.class
+.idea/
+*.iml
+target/
+
+.classpath

Java/pom.xml

@@ -24,6 +24,13 @@
 
     <build>
         <plugins>
+            <plugin>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <configuration>
+                    <source>1.8</source>
+                    <target>1.8</target>
+                </configuration>
+            </plugin>
         </plugins>
     </build>