Fixed edge case for getPathForDescendantQuery

- e.g. $qomf->descendantNode("/") now works
- Some other random fixes
  - Fixed typo in DocBlocks
  - Command doctrine:phpcr:query
      - Display language when executing query via  (I
        was wondering why my query wasn't working, it was being executed as
        JCR_SQL2 and not SQL)
      - Display query execution time