[MOJO-2066] Set Java version via mojo.java.target.
[MOJO-2066] Set Java version via mojo.java.target.

The properties maven.compiler.source and maven.compiler.target are used
by the compiler plugin only. mojo.java.target is used by the Plugin
plugin and the PMD plugin, too.

git-svn-id: 8d132e1a15335a2a79fbd300913f3731fbab67c7@20394 52ab4f32-60fc-0310-b215-8acea882cd1b

mojohaus/tidy-maven-plugin