Use Traits

[tcyrus]

• Implemented From and TryFrom traits so that DsaPrivateKey, EcdsaPrivateKey, and OpaquePrivateKeyBytes can be created from bytes without needing the encoding::Decode trait (ssh-key doesn't export ssh-encoding, so I had some issues with this).
• Implemented functions for PrivateKey and PublicKey using std::io::{Write, Read} traits (std only). This allows you to read / write files without needing to provide a path
• Use AsRef<Path> instead of &Path for PrivateKey and PublicKey

I'd appreciate it if this could be back-ported to 0.6.x. The v0.7.0-rc.0 release isn't working for me.

[tarcieri]

ssh-key doesn't export ssh-encoding, so I had some issues with this

Surprised to hear that. Opened #379.

The v0.7.0-rc.0 release isn't working for me.

What problems are you having?

[tcyrus]

Just rebuilt my tool and it looks like a basic version conflict.
I thought it was something different, but I guess not.

[tarcieri]

@tcyrus I actually noticed a bug in the recent release of the elliptic curve crates and fixed it and cut another release, so hopefully that was the solution

[tcyrus]

Forgot to push this out, but it might be a good idea for read_openssh_file and write_openssh_file to use read_openssh and write_openssh respectively.