problematic byteorder version

[ZijianHe]

Should probably undo this change since this change basically prevents people using a higher version of Rust from directly or indirectly having a higher version of byteorder in their dependencies.

In my case I've got this error:

Caused by:
  failed to select a version for `byteorder`.
      ... required by package `bincode v1.3.2`
      ... which is depended on by `xxxxxx`
  versions that meet the requirements `>=1.3.0, <1.4.0` are: 1.3.4, 1.3.3, 1.3.2, 1.3.1, 1.3.0

  all possible versions conflict with previously selected packages.

    previously selected package `byteorder v1.4.2`
      ... which is depended on by `rmp v0.8.10`
      ... which is depended on by `rmp-serde v0.15.4`
      ... which is depended on by `xxxxxx`

  failed to select a version for `byteorder` which could resolve this conflict

[VictorKoenders]

See #380 for more information on this

Currently bincode supports rust 1.18 and up, and byteorder released a version that is not compatible with this. We're working on a (breaking) change version that has a higher minimum rust version that fixes this.