Invenio-communities

- parent_community: dereference parent community
- parent: dereference in systemfield
- theme: handle null values
- parent_community: fix derefencing

- mappings: update to theme.style
- systemfields: add parent community
- community: add theme.enabled flag
- community: rename theme.config to theme.style to facilitate indexing
- records: expose theme field in search
- mappings: add "parent" community and normalize funding
- global: always serialize Community.theme
- models: add index on bucket_id

- installation: bump dependencies

- global: add support for community theming
- adds new data field called `theme`
- adds specific template loader that handles themed templates per community
- enables feature only for system user at the moment programmtically
- disables indexing of community theme information

- replaced ckeditor with tinymce due to license issue
- split CommunitiesCardGroup definition and rendering
- changed "featured-communities" id on communities frontpage to "new-communities".
WARNING: If you are overriding invenio-communities/frontpage.html, make that change in your template.

- assets: add overridable id to profile form
- assets: increase the char limit on community page description