Fix compatibility with recent versions of Java plugin

[simonbrandhof]

Clirr plugin requires the Java plugin to be installed too. The recent versions of Java plugin, at least the version 3.13.1 which is packaged by default with SonarQube 5.6, make integration of Clirr report fail:

Caused by: java.lang.NoSuchMethodError: org.sonar.plugins.java.api.JavaResourceLocator.findResourceByClassName(Ljava/lang/String;)Lorg/sonar/api/resources/Resource;
    at org.sonar.plugins.clirr.ClirrSensor.saveIssues(ClirrSensor.java:94)
    at org.sonar.plugins.clirr.ClirrSensor.analyse(ClirrSensor.java:76)
    at org.sonar.batch.phases.SensorsExecutor.executeSensor(SensorsExecutor.java:58)
    at org.sonar.batch.phases.SensorsExecutor.execute(SensorsExecutor.java:50)
    at org.sonar.batch.phases.AbstractPhaseExecutor.execute(AbstractPhaseExecutor.java:83)
    at org.sonar.batch.scan.ModuleScanContainer.doAfterStart(ModuleScanContainer.java:192)
    at org.sonar.core.platform.ComponentContainer.startComponents(ComponentContainer.java:142)
    at org.sonar.core.platform.ComponentContainer.execute(ComponentContainer.java:127)
    at org.sonar.batch.scan.ProjectScanContainer.scan(ProjectScanContainer.java:241)
    at org.sonar.batch.scan.ProjectScanContainer.scanRecursively(ProjectScanContainer.java:236)
    at org.sonar.batch.scan.ProjectScanContainer.doAfterStart(ProjectScanContainer.java:226)
    at org.sonar.core.platform.ComponentContainer.startComponents(ComponentContainer.java:142)
    at org.sonar.core.platform.ComponentContainer.execute(ComponentContainer.java:127)
    at org.sonar.batch.task.ScanTask.execute(ScanTask.java:47)
    at org.sonar.batch.task.TaskContainer.doAfterStart(TaskContainer.java:86)
    at org.sonar.core.platform.ComponentContainer.startComponents(ComponentContainer.java:142)
    at org.sonar.core.platform.ComponentContainer.execute(ComponentContainer.java:127)
    at org.sonar.batch.bootstrap.GlobalContainer.executeTask(GlobalContainer.java:106)
    at org.sonar.batch.bootstrapper.Batch.executeTask(Batch.java:119)
    at org.sonarsource.scanner.api.internal.batch.BatchIsolatedLauncher.execute(BatchIsolatedLauncher.java:62)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.sonarsource.scanner.api.internal.IsolatedLauncherProxy.invoke(IsolatedLauncherProxy.java:60)
    at com.sun.proxy.$Proxy21.execute(Unknown Source)
    at org.sonarsource.scanner.api.EmbeddedScanner.doExecute(EmbeddedScanner.java:240)
    at org.sonarsource.scanner.api.EmbeddedScanner.runAnalysis(EmbeddedScanner.java:151)
    at org.sonarsource.scanner.maven.bootstrap.ScannerBootstrapper.execute(ScannerBootstrapper.java:78)
    at org.sonarsource.scanner.maven.SonarQubeMojo.execute(SonarQubeMojo.java:112)
    at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:132)
    ... 20 more