- Fixed integration test
  - Added missing check operation of output during integration
    test mexec-29-wrong-signature.

git-svn-id: https://svn.codehaus.org/mojo/trunk/mojo/exec-maven-plugin@19356 52ab4f32-60fc-0310-b215-8acea882cd1b
[MEXEC-104]
  - Added new parameter failWithEmptyArgument
    to control the behaviour and to keep compatibility
    with earlier version and giving the
    opportunity to change it.
    Added two integration tests.

git-svn-id: https://svn.codehaus.org/mojo/trunk/mojo/exec-maven-plugin@19357 52ab4f32-60fc-0310-b215-8acea882cd1b