renaming plugin and test files; plugins are now in individual subdirectories (ref. #50)

service-worker.js

@@ -251,7 +251,7 @@ let initServiceWorker = async () => {
             // load the relevant plugin script (if not yet loaded)
             if (!LibResilientPluginConstructors.has(pluginConfig.name)) {
                 self.log('service-worker', `${pluginConfig.name}: loading plugin's source`)
-                self.importScripts(`./plugins/${pluginConfig.name}.js`)
+                self.importScripts(`./plugins/${pluginConfig.name}/index.js`)
             }
             
             // do we have any dependencies we should handle first?