Use saved promise instead of userInfoCache.

- Use saved promise instead of userInfoCache. The advantage of this approach is that entire response is saved including error message when API call fails. The error message is needed in CH to determine is user accepted terms.
- Add missing "mailSyncEnabled" field ( https://github.com/Rise-Vision/ng-core-api-client/compare/chore%2Freplace-userinfocache-by-saved-promise?expand=1#diff-87bf02cb6b296d9354e5af132026785fR95 )

@settinghead please review.