Issue #2214313 by chx, ultimike, benjy | eliza411: Contact: Not all values are being migrated.

.../config/install/migrate.migration.d6_contact_category.yml

.../config/install/migrate.migration.d6_contact_settings.yml

.../Drupal/migrate_drupal/Plugin/migrate/source/Variable.php

...grate_drupal/Plugin/migrate/source/d6/ContactCategory.php

...grate_drupal/Plugin/migrate/source/d6/ContactSettings.php

...upal/migrate_drupal/Tests/Dump/Drupal6ContactCategory.php

...al/migrate_drupal/Tests/d6/MigrateContactCategoryTest.php

...pal/migrate_drupal/Tests/d6/MigrateContactConfigsTest.php

...al/migrate_drupal/Tests/source/d6/ContactCategoryTest.php