Make config file a global

Signed-off-by: Jani Monoses <jani@ubuntu.com>
More error checks and messages

Signed-off-by: Jani Monoses <jani@ubuntu.com>
Generate channels.json based on config.ini

Signed-off-by: Jani Monoses <jani@ubuntu.com>
Add example config section for channels and devices

Signed-off-by: Jani Monoses <jani@ubuntu.com>