Bug 952488 permissions

Add reviewed attribute to the Translation module. Set to true on import from repository or manually by privileged user. When displaying and exporting translations, if reviewed translation doesn't exist, use latest unreviewed translation.

Non-privileged users can:
 * submit translations
 * delete their own translations if not approved

Privileged users can:
 * submit reviewed translations
 * delete all translations
 * approve translations
 * commit to SVN

Open history instead of machinery by default. Save translation authors as user objects instead of email.