Fix issue in PoFileParser where only slashes from translations of type array are stripped.

I was experiencing an issue using a .po file only setup (no .mo files) where translated escaped data was not stripped of slashes.

This PR should fix the issue.

Original msgid: 
``msgid "Not a member yet? Please register <a href=\"{0}\">here</a>."```

Translated Before fix:
``Noch kein Mitglied? <a href=\"{0}\" target=\"_blank\">Hier</a> kannst du```

Translated after fix:
``Noch kein Mitglied? <a href="{0}" target="_blank">Hier</a> kannst du ``

as present in PO file:
```
#: Template/Workshops/subscribe.ctp:18
msgid "Not a member yet? Please register <a href=\"{0}\">here</a>."
msgstr ""
"Noch kein Mitglied? <a href=\"{0}\" target=\"_blank\">Hier</a> kannst du "
"dich anmelden."
```