Add Gist Support

[mmstick]

Adds support for executing Rust scripts from GitHub, Gists and other raw HTTP sources.

[DanielKeep]

Just checking up: are you working on the build failures for 1.4 and 1.5?

[DanielKeep]

Also, looking at curl: I'm not a fan of how it requires users to download the entire source tree for libcurl and potentially build it from scratch. For me, I couldn't even get it to do that: it just failed to build, and I'm not really sure why.

I'm going to look into some kind of simple "geturl" crate, because it's something I've wanted quite a few times.

[mmstick]

I don't support any versions lower than the current stable release, and according to the build logs, the errors are unavoidable because the dependencies require features that are not supported in those older versions of Rust. I don't think I can even install anything less than the stable version with multirust.

You'll always need to have the C development libraries installed when using that library in Rust, or any programming language for that matter. There are no pure-Rust implementations of OpenSSL and Curl at this time.

[nertpinx]

Since this is couple of weeks old, I'll just mention that reqwest has support for various TLS backends.