[ticket/12834] Fix tests to match what we want to have

PHPBB3-12834
[ticket/12834] Correctly match directories in session page

Also clean path before working with it

PHPBB3-12834
Merge remote-tracking branch 'nickvergessen/ticket/12834' into develop-ascraeus
Merge pull request #2675 from lucifer4o/ticket/12786

[ticket/12786] Extend profilefield_base_migration.php class

* lucifer4o/ticket/12786:
  [ticket/12786] Correcting some tabs
  [ticket/12786] Array_merge instead copy array parts
  [ticket/12786] Some changes of the comments.
  [ticket/12786] Dixing a typo
  [ticket/12786] Some minor fixes of comments and function naming
  [ticket/12786] Add clean_cpf_db_entries
  [ticket/12786] White spaces found
  [ticket/12786] Add create_language_entries
  [ticket/12786] Add get_custom_field_id
  [ticket/12786] Extend profilefield_base_migration.php class