fix(cargo): Bump dependencies so that Tokio compiles with minimal versions

[klausi]

I'm working on minimal version installer for cargo, turns out some dependencies are out of date:

cargo build -Z minimal-versions
   Compiling libc v0.1.0
error: expected identifier, found `"std"`
  --> /home/klausi/.cargo/registry/src/github.com-1ecc6299db9ec823/libc-0.1.0/rust/src/liblibc/lib.rs:76:46
   |
76 | #[cfg(feature = "cargo-build")] extern crate "std" as core;
   |                                              ^^^^^ expected identifier

error: aborting due to previous error

error: Could not compile `libc`.

   Compiling bytes v0.4.0                                                       
error[E0432]: unresolved import `bytes::buf::Chain`
 --> tokio-io/src/length_delimited.rs:4:5
  |
4 | use bytes::buf::Chain;
  |     ^^^^^^^^^^^^^^^^^ no `Chain` in `buf`

Updating log to 0.4 as in the other tokio crates here and updating bytes to fix the type errors.

[carllerche]

Thanks for the report! A minimal version installer would definitely be helpful to catch these issues.

[klausi]

Yep, we are almost there at rust-lang/cargo#5200 :-)

[carllerche]

Would you be able to merge master? This should hopefully fix CI.

[klausi]

Done, rebased this on master.

Ideally we should add cargo build -Z minimal-versions somewhere in the Travis CI config, but that does not work yet on Rust nightly:

$ cargo build -Z minimal-versions
error: unknown `-Z` flag specified: minimal-versions
$ cargo --version
cargo 1.26.0-nightly (d10ec661b 2018-03-20)

I need to find out when cargo nightly is pushed downstream to Rust nightly.

[carllerche]

Thanks. It should be soon. Let's see if it lands tomorrow.

[carllerche]

Did this land?

[carllerche]

I merged, but I would love to get this added to CI.

[Eh2406]

ping! it is on nightly (for a while now) feel free to add it to CI!