Change the way to configure Sonar Ant Task

In order to be consistent accross the different bootstrappers: starting with Sonar Ant Task 1.5, the standard way to configure the task will be through properties only (= the exact same way to configure the Sonar Runner, that will actually be embedded in the Ant Task).

The old way will still be supported as a compatibility mode, but is bound to be removed in a near future. Everytime the task is run in compatibility mode, a warning message is logged to encourage users to update their scripts.

Example of old way:

...
  <target name="sonar">
    <sonar:sonar key="my-project" version="0.1-SNAPSHOT">
      <property name="sources" value="src"/>
    </sonar:sonar>
  </target>
...

New standard way:

...
  <property name="sonar.projectKey" value="my-project"/>
  <property name="sonar.projectName" value="My Project"/>
  <property name="sonar.projectVersion" value="0.1-SNAPSHOT"/>
  <property name="sonar.sources" value="src"/>
...
  <target name="sonar">
    <sonar:sonar />
  </target>
...