Bump dependencies, except for diesel master

Overall this consolidates duplicate versions of `base64` and `chrono`.

The following commands were run:

```
cargo update -p openssl --aggressive
cargo update -p ammonia --aggressive
cargo update -p lettre --aggressive
cargo update -p tokio-core --aggressive
cargo update -p hyper --aggressive
cargo update -p itertools --aggressive
cargo update -p serde_derive -p serde_json -p filetime --aggressive
cargo update -p curl -p git2 --aggressive
cargo update -p backtrace -p cookie -p miniz-sys --aggressive
cargo update -p twoway -p schannel -p memchr:1.0.1 --aggressive
```

Author: jtgeibel