Fixed typos

src/Writer/AbstractWriter.php

@@ -150,7 +150,7 @@ public function setFormatter(Formatter $formatter)
     }
 
     /**
-     * Perform shutdown activites such as closing open resources
+     * Perform shutdown activities such as closing open resources
      *
      * @return void
      */

src/Writer/MongoDB.php

@@ -63,13 +63,13 @@ public function __construct($mongo, $database, $collection, array $saveOptions =
             $collection  = isset($mongo['collection']) ? $mongo['collection'] : null;
             if (null === $collection) {
                 throw new Exception\InvalidArgumentException(
-                    'The collection parameter cannot be emtpy'
+                    'The collection parameter cannot be empty'
                 );
             }
             $database = isset($mongo['database']) ? $mongo['database'] : null;
             if (null === $database) {
                 throw new Exception\InvalidArgumentException(
-                    'The database parameter cannot be emtpy'
+                    'The database parameter cannot be empty'
                 );
             }
             $mongo = isset($mongo['mongo']) ? $mongo['mongo'] : null;