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

public/css/style.scss

@@ -1664,11 +1664,11 @@ div[data-overlayscrollbars-viewport="scrollbarHidden"] > .navbar-nav > li#market
   }
 }
 
-#showClaimInstructions {
+.instructions {
   color: #ffffff;
 }
 
-#showClaimInstructions:hover {
+.instructions:hover {
   color: #efefef;
 }