Run tests using cargo hack

[npmccallum]

This dynamically ensures that the various combinations of features flags
successfully work.

Signed-off-by: Nathaniel McCallum nathaniel@profian.com

[npmccallum]

Please note that this PR is intended to reveal existing breakage.

[franziskuskiefer]

Thanks @npmccallum

The no_std support for tls_codec isn't really there yet (see #64). We can either disable default features on serde for no_std or not check for the serde_serialize feature on no_std platforms.

info: running `cargo build --release --target thumbv7em-none-eabi --no-default-features --features serde_serialize` on tls_codec (2/2)
   Compiling serde_derive v1.0.133
   Compiling serde v1.0.133
error[E0463]: can't find crate for `std`
  |
  = note: the `thumbv7em-none-eabi` target may not support the standard library
  = note: `std` is required by `serde` because it does not declare `#![no_std]`

[npmccallum]

@franziskuskiefer I took a slightly different approach. Let me know if this doesn't work.

[franziskuskiefer]

@franziskuskiefer I took a slightly different approach. Let me know if this doesn't work.

That works as well. Thanks!