Remove new line chars when create linfo files

If a translator add a '\n' char in the summary translation
ConfigParser can't parse the linfo file.
Remove them when the file is created and show a message to warning
to the developer.

src/sugar3/activity/bundlebuilder.py

@@ -144,6 +144,11 @@ class Builder(object):
             cat = gettext.GNUTranslations(open(mo_file, 'r'))
             translated_name = cat.gettext(self.config.activity_name)
             translated_summary = cat.gettext(self.config.summary)
+            if translated_summary.find('\n') > -1:
+                translated_summary = translated_summary.replace('\n', '')
+                logging.warn(
+                    'Translation of summary on file %s have \\n chars. '
+                    'Should be removed' % file_name)
             linfo_file = os.path.join(localedir, 'activity.linfo')
             f = open(linfo_file, 'w')
             f.write('[Activity]\nname = %s\n' % translated_name)