[FIX] Changed 'Add new server' to 'Add New Server' (RocketChat#591)

Makes sense given that the UX features a hover for the 'Create a New Channel' with caps.

Author: HammyHavoc

src/i18n/lang/en.i18n.json

@@ -2,7 +2,7 @@
     "About": "About %s",
     "Add": "Add",
     "Add_host_to_servers": "Do you want to add \"%s\" to your list of servers?",
-    "Add_new_server": "Add new server",
+    "Add_new_server": "Add New Server",
     "Add_Server": "Add Server",
     "Application_Reload": "Application - Reload",
     "Application_Toggle_DevTools": "Application - Toggle DevTools",