Merge pull request #215 from bvssvni/master

Fixed bug in iterator
Merge pull request #216 from bvssvni/master

Upgraded examples to latest Rust
Merge pull request #218 from bvssvni/master

Removed `Load` from `GameIterator`
Merge pull request #221 from bvssvni/master

Removed `AssetStore` from `GameIterator`
Removed unnecessary lifetimes

Closes https://github.com/PistonDevelopers/piston/issues/222