Set /app PHP code to PSR-2 standard

Also adde draw.io to attribution list.

Closes #649

app/Providers/PaginationServiceProvider.php

@@ -1,6 +1,5 @@
 <?php namespace BookStack\Providers;
 
-
 use Illuminate\Pagination\PaginationServiceProvider as IlluminatePaginationServiceProvider;
 use Illuminate\Pagination\Paginator;
 
@@ -32,4 +31,4 @@ class PaginationServiceProvider extends IlluminatePaginationServiceProvider
             return 1;
         });
     }
-}
+}