Invenio-userprofiles

- Unpin Flask 2

- Adds german translations

- Add config option to make user profiles form read-only

- Add theme dependent icons.

- Marked strings for translation
- Added Turkish translation
- Changes `cancel` button's color
- Integrates Semantic-UI templates
- Removes example app

- Minimum version of Invenio-Accounts bumped to v1.2.1 due WTForms moving the
email validation to an optional dependency