Make sure the DIRROOT constant ends with a /
Make sure the DIRROOT constant ends with a /

This should make is easier to use it.

Re: #2591

Picked from b6d9edbb49

bauhouse/sym-todo-list,michael-e/symphony-2,bauhouse/sym-todo-list,symphonycms/symphony-2,symphonycms/symphony-2,jensscherbl/symphony,jensscherbl/symphony,michael-e/symphony-2