NS driver: Use NS's random number generator when possible.

Original patch by Sascha Alexander Jopen.
Make libclick compile.
Place libclick dependencies in .deps.
Whoops: remove a directory correctly.
Libclick: Include a .gitignore.
Improve libclick make clean targets.
Configury nit.
NS: Fetch defines from the NS simulator.

Requires very recent versions of ns-3, but works anywhere.

Signed-off-by: Eddie Kohler <ekohler@gmail.com>