Merge pull request #136 from bvssvni/master

Upgrade to latest Rust
Fix osx+pkg-config build with rust-empty.mk file
Merge pull request #137 from jdeseno/master

Fix osx+pkg-config build with rust-empty.mk file
Add Cargo support
Merge pull request #138 from jdeseno/cargo

Add Cargo support
Upgraded to latest Rust-Empty