Update-able version, tested on Redmine 2.5.2

Update-able settings, (tracker, status, priority) labels are read from the Redmine DB, only admins can update.
The "Issue Color Label" menu item in available in the Administration page.

The plugin can be enabled / disabled.
Settings are stored in a (writable) configuration.json file, for now.

Working version, tested using Redmine 2.5.2

0.1

working version