Accept custom config location in system.sh

[hamishfagg]

Describe the bug system.sh does not support custom config locations

To Reproduce Steps to reproduce the behavior:

1. Run mopidy with a custom config --config
2. Click on local scan in Iris
3. Fails due to trying to use default config location

Expected behavior Use the current config location being used by mopidy

Additional context Out of curiosity, does mopidy's interface for front-ends not support running a scan? Why do we need the shell script?

[jaedb]

Correct - a rescan can only be triggered by the mopidyctl local scan or (mopidy local scan if not running as a service), hence this rather crude workaround.