Add preliminary plugin support

-Plugins can now be enabled via settings.json after dropping the plugin files into the new plugins directory
-Enabling plugins will allow extending the normal functionality of the explorer with new database collections, menus, pages and apis + open up a new url for data to be sent from the plugin to the explorer
-A new plugins section was added to the settings with a definition for the generic-snapshots plugin
-Locale strings are now loaded and shared out via the settings so there is generally no more need to explicitly include the locale.js file
-The locale object has been updated to localization within the explorer
-A number of new locale strings have been added and their values replaced with the locale string within the explorer
-Added plugin support verbiage and a link to the generic-snapshots crowdfunding task to the README

scripts/stop_explorer.js

@@ -47,7 +47,7 @@ if (validate_port(settings.webserver.port) == true) {
       // send a kill signal to the process that is currently using the explorer's server port
       exec(killcmd, (err, stdout, stderr) => {
         // show shutdown msg
-        console.log('Explorer shutting down... Please wait...');
+        console.log(`${settings.localization.explorer_shutting_down}.. ${settings.localization.please_wait}..`);
         process.exit(0);
       });
     } else {