[MCOMPILER-157] Add generated sources directory as compile/testCompile source root after annotation processor runs. This includes an integration test that uses a custom annotation processor to generate text files based on annotated classes, and a custom plugin to verify that these text files are available via project.getCompileSourceRoots() / project.getTestCompileSourceRoots().

git-svn-id: https://svn.apache.org/repos/asf/maven/plugins/trunk@1629322 13f79535-47bb-0310-9956-ffa450edef68