SymbolicResponse i18n.

Ticket [BLD-721](https://edx-wiki.atlassian.net/browse/BLD-721)

Result for SymbolicResponse:
```
#. Translators: 'SymbolicResponse' is a problem type and should not be
#. translated.
#: common/lib/capa/capa/responsetypes.py:1786
msgid "oops in SymbolicResponse (cfn) error"
msgstr ""
```
@olmar please review.