Add PluginBase::onDeactivate method
Merge branch 'onDeactivate-plugin-method' into git-annex-plugin
Uninit git-annex repository when GitAnnex plugin is deactivated
Add GitAnnexPlugin::init method

This method is called once after the plugin has been activated.
Added script for initial git-annex configuration
Merged git-annex-plugin in git-annex-backend