In the past the class InstallJavascriptsTask was used for installing all JS.
In 1.2 it was 'miss'used to update them too.
The drawback of this was, that possible changes within the JSs would just be overwritten.
On the other hand subclassing this class for all new STK version lead to impossibility to see the deltas in between versions.

New mechanism:
JavascriptsVersionsMap -> hold now all the scripts-versions (not InstallJavascriptsTask anymore) for all version ever.
InstallJavascriptsTask -> only used for installs and not delta updates.
UpdateJavascriptsTask -> used for updating all JSs in between two versions. (backups and removes old scripts)
UpdateSingleJavascriptTask -> used for updating a single JS or installing a new one for delta update tasks. (backups and removes old script)