feat: Improved start script

[vbakke]

Fixes #28.

As part of streamlining the scart script, I also found out how to fix the issue #28. You had already made a comment in the meta-on-top branch, and as comments in the bash script.

With this PR, one can use:

    ./generateDimensions.bash --install       First time, install composer dependencies
    ./generateDimensions.bash                 Generate activities.yaml
    ./generateDimensions.bash --test-urls     Test URLs in implementations.yaml
    ./generateDimensions.bash --start-dsomm   Start a local DSOMM app

[vbakke]

I have written the README file referencing to the new activities.yaml, which I think will a correct shortly.
However, the --start-dsomm is still referencing to generated.yml. So we have to review this again when we release v4, @wurstbrot