Adding Marian version to models about marian-dev

[emjotde]

@tomekd @snukky @hieuhoang
Should this just be a numeric value that we increase manually whenever a breaking change gets implemented?

[tomekd]

I can add git commit hash to the model.

[geovedi]

i'm suggesting the use of semantic versioning integrated with release tag so people can create distro package.

[snukky]

I also think that git commit hash won't work as a version number in that case. A better option would be adding global versioning in CMake.

[snukky]

Project version is now available with PROJECT_VERSION. It uses tag versions if available.

[snukky]

Done.