implement servo --version , and include the compilation date

[paulrouget]

In the browserhtml team, we use servo nightly builds, and it's always difficult to know which version of servo one is currently using.

Could we have a --version option, that would return something like:

$ servo --version
Servo 0.0.1 - compiled 2016-05-27

[campaul]

I'm interested in working on this.

[paulrouget]

@campaul Thanks! Command line options are defined here: https://github.com/servo/servo/blob/master/components/util/opts.rs

[jdm]

The only idea I have for including the build date is to write it to a file in build.rs and use that file via the include_str! macro.

[campaul]

I'm using env!("CARGO_PKG_VERSION"); to get the version number, so I was thinking I could do something similar and have mach set an environment variable with the current date.

[jdm]

That might work too!