Installer language selector changed

In Drupal 7, the installer language selector shows up right after the install profile is selected. Drupal 8 centralizes the translations files directories into one directory (see http://drupal.org/node/1352228 for more information) and consequently moves the language selector to the first step of the installer. This means hook_install_tasks_alter() implemented in the install profile cannot alter the language selector form anymore. Further work on this is being done in #1386394: Add back the ability for install profiles (or at least distros) to pre-select a language or modify the language-selection screen and #1351352: Distribution installation profiles are no longer able to override the early installer screens.