Invenio-records-rest

- Changes ``str`` to ``text_type`` on filter dsl.

- Adds source filtering support for ES 5.

- Adds PersistentIdentifier field to handle record PIDs.
- Adds Nested class to improve reporting of validation errors.

- Rename authentication of GET operation over
RecordsListResource from 'read_list' to 'list'.

- Adds authentication to GET operation over
RecordsListResource.
- Bumps invenio-db version (min v1.0.2).

- Moves RecordSchemaJSONV1 marshmallow schema from
invenio_records_rest.serializers.schemas to
invenio_records_rest.schemas.
- Fixes missing API documentation.
- Adds blueprint factory (requires Invenio-Base v1.0.1+).
- Adds marshmallow loaders, fields and schemas.