* Create `CorsOptions`
- `Cors` will be, in the future, an "optimised" or "compiled" version of
`CorsOptions`
- For now, `Cors` simply clones `CorsOptions` and `Deref`s to
`CorsOptions`.
* Update examples
* Remove usage of `Self` struct constructors
* Remove macro_use from examples
* Remove macro_use from log and rocket
* Remove macro_use for serde_derive
* Remove from examples
* Fix no-default features build failure
* Update Cargo.toml for Rocket `master`
* Prepare library for Rocket 0.4
TODO: check line 62 in `fairing.rs` to find better way than unwrapping
* Bump minimum nightly for Rocket 0.4
Yong Wen Chua
Eric Dattore