Fix Maven integration tests

[tmortagne]

Here are the fixed problems:

• Looks like commons-codec is in fact used (indirectly probably) and since the shade plugin is configured to rename all references to org.apache.commons I included it (if you are sure it's only use in the Maven use case I guess an alternative would be to configure the shade plugin with a more restrictive package to rename)
• The mojo seems to need a class located in ant so it cannot be scope provided
• The mojo have a direct dependency on a class located in plexus-sec-dispatcher (to be honest I don't fully understand this one as plexus-sec-dispatcher seems to be part of Maven itself so not sure why it cannot find it, but adding this dependency definitely fix the class not found...)

[tmortagne]

I also suggest #627 since the required Maven version seems a bit low for the shade plugin (seems to be what is causing the AppVeyor failure).

[tcurdt]

I think it's time to port the windows test over to github anyway.
No point to deal with appveyor anymore.