Add content for all 3 Send buttons (2 are the same as far as I can tell)

actions/invite.php

@@ -194,7 +194,7 @@ class InviteAction extends CurrentUserDesignAction
                         _('Optionally add a personal message to the invitation.'));
         $this->elementEnd('li');
         $this->elementEnd('ul');
-        $this->submit('send', _m('invite button', 'Send'));
+        $this->submit('send', _m('Send button for inviting friends', 'Send'));
         $this->elementEnd('fieldset');
         $this->elementEnd('form');
     }

lib/messageform.php

@@ -175,6 +175,6 @@ class MessageForm extends Form
                                            'class' => 'submit',
                                            'name' => 'message_send',
                                            'type' => 'submit',
-                                           'value' => _('Send')));
+                                           'value' => _m('Send button for sending notice', 'Send')));
     }
 }

lib/noticeform.php

@@ -233,6 +233,6 @@ class NoticeForm extends Form
                                            'class' => 'submit',
                                            'name' => 'status_submit',
                                            'type' => 'submit',
-                                           'value' => _('Send')));
+                                           'value' => _m('Send button for sending notice', 'Send')));
     }
 }