[MEXEC-137] add IT mexec-137, apply patch provided by Piet van Dongen. However, the patch is disable since the test is happy without the patch.  Need further investigation

git-svn-id: https://svn.codehaus.org/mojo/trunk/mojo/exec-maven-plugin@19752 52ab4f32-60fc-0310-b215-8acea882cd1b
[MEXEC-137] activate the patch and comment why we need to invoke it with 'cmd /c'

git-svn-id: https://svn.codehaus.org/mojo/trunk/mojo/exec-maven-plugin@19753 52ab4f32-60fc-0310-b215-8acea882cd1b
[MEXEC-136] remove windows specific config to get IT to pass on both unix and windows

git-svn-id: https://svn.codehaus.org/mojo/trunk/mojo/exec-maven-plugin@19754 52ab4f32-60fc-0310-b215-8acea882cd1b
[MEXEC-118] search for windows .cmd script provided by Mikael Ståldal

git-svn-id: https://svn.codehaus.org/mojo/trunk/mojo/exec-maven-plugin@19758 52ab4f32-60fc-0310-b215-8acea882cd1b