Add blockexplorer side panel

This is a request to include HiveBlocks.com into the sidepanel. It has been requested by many community members where the Blockexplorer is, and it seems logical we include it in the sidepanel. Also locals have been updated for new key.

src/app/components/modules/SidePanel/index.jsx

@@ -62,6 +62,10 @@ const SidePanel = ({
                 label: tt('navigation.faq'),
                 link: `/faq.html`,
             },
+            {
+                label: tt('navigation.block_explorer'),
+                link: `https://hiveblocks.com`,
+            },
             /*
             {
                 label: tt('navigation.explore'),