Fix manipulate.translation ignore behaviour

[kasimircash]

Changes proposed in this pull request:

When using cli/manipulate.translation.php we would expect that cli/manipulate.translation.php -a ignore -l en -k install.auth.form would add an ignore note to the key install.auth.form and that cli/manipulate.translation.php -a ignore -l en -k install.auth.form -r would remove the ignore note from install.auth.form. Instead, this behaviour is reversed. This same reversed behaviour is present when using -a ignore_unmodified with cli/manipulate.translation as well.

This fix gives us the behaviour from cli/manipulate.translation.php that we would expect e.g. the reverse of current behaviour.

I've also modified the tests for ignore and ignore_unmodified in I18nDataTest.php as they were checking for the incorrect output.

How to test the feature manually:

1. Use cli/manipulate.translation.php -a ignore -l en -k install.auth.form to ignore a key.

2. Check the translation file (in this case FreshRSS/app/i18n/en/install.php) to confirm the key is ignored.
   

3. Use cli/manipulate.translation.php -a ignore -l en -k install.auth.form -r to remove the ignore note.

4. Confirm the key has been unignored.
   

Pull request checklist:

• clear commit messages
• code manually tested
• unit tests written

[Alkarex]

Pinging @aledeg if you are around