Don't include API version in SALSA_URL variable

I think it would be better to not put the API version in the SALSA_URL variable in salsarc.

If it needs to be specific, use a separate variable. This could make the fix for #2 (closed) easier.

But I think the API version is an implementation detail that users shouldn't need to change, so I recommend including it in the scripts instead of the user configuration file.