remove cobertura plugin since it doesn't support jdk 8

pom.xml

@@ -403,15 +403,6 @@
 							</execution>
 						</executions>
 					</plugin>
-					<plugin>
-						<groupId>org.codehaus.mojo</groupId>
-						<artifactId>cobertura-maven-plugin</artifactId>
-						<configuration>
-							<format>xml</format>
-							<maxmem>256m</maxmem>
-							<aggregate>true</aggregate>
-						</configuration>
-					</plugin>
 					<plugin>
 						<groupId>org.eluder.coveralls</groupId>
 						<artifactId>coveralls-maven-plugin</artifactId>
@@ -513,14 +504,6 @@
 				<artifactId>findbugs-maven-plugin</artifactId>
 				<version>3.0.3</version>
 			</plugin>
-			<plugin>
-				<groupId>org.codehaus.mojo</groupId>
-				<artifactId>cobertura-maven-plugin</artifactId>
-				<version>2.7</version>
-				<configuration>
-					<aggregate>true</aggregate>
-				</configuration>
-			</plugin>
 		</plugins>
 	</reporting>
 </project>