Update to the last rust-nightly.

Version of rustc: 0.11.0-pre-nightly (6a3695d54f14491c39da7910082df9ba9c833b37 2014-06-29 00:31:30 +0000)
Update nphysics (without the examples) to the last rust-nighty.

Version of rustc: 0.11.0-pre-nightly (5d5c20647f45f2eb74f337e5434bbe63b0c43345 2014-07-03 21:46:47 +0000).