Add build system

[mitchr]

[jwortmann]

I'm not sure whether this repository is still maintained due to the missing reactions on pull requests, but I think it would be nice to ship a build system by default. The file suggested here has some issues though:

• "shell_cmd" requires a single string, and not an array. Alternatively, only "cmd" could be used instead.
• The "selector" must be source.julia and not source.jl

Therefore I would suggest to use the following build file:

{
    "cmd": ["julia", "--project=@.", "$file"],
    "working_dir": "$file_path",
    "selector": "source.julia"
}

[StefanPofahl]

I agree, it would be nice to add this feature!!!