[MEXEC-129]
  - added missing provided scope for maven-plugin-annotations.

git-svn-id: https://svn.codehaus.org/mojo/trunk/mojo/exec-maven-plugin@19466 52ab4f32-60fc-0310-b215-8acea882cd1b
[MEXEC-118]
 - Added handling of .bat/.cmd/.exe etc.
 - Enhanced code to check for null parameter and
   added appropriate unit tests in relationship
   with EXEC-80 (commons-exec).