Expose omnisharp options via the settings in the omnisharp-atom plugin

[davidfowl]

Any setting allowed on config.json (lives in the omnisharp server) or omnisharp.json (lives in the user project) can be specified as arguments to the omnisharp-roslyn server on startup. We should expose the common settings and that should trigger a restart of any running server and it should pass those arguments on startup.

[nosami]

This sounds like an excellent idea.

Maybe we need a schema for config so that we know how to render the ui (checkbox, input or select) for each setting?

Also, restarting the server for a config change seems like a cop out. We should be able to change server config on the fly.