Add a package that installed the pre-built maven distribution.

I've given up, for now, on building maven from source.  That processed
stumbled on two points before I gave up:

1. It downloaded several hundred .{pop,jar} files and I despaired of
   figuring out some way of mirroring and checksumming them; and

2. It exploded complaining about too many unacceptable license files,
   which seems odd in its own source tree.

Perhaps someone with more Java fu that I admit to can figure it out.
In the meantime, this is useful.