Entity form and view modes moved from Entity module to Core

- Core change notice: https://www.drupal.org/node/2335315
Merge pull request #72 from Jbekker/remove-entity-dependency

Entity form and view modes moved from Entity module to Core
Rename FieldInstanceConfig to FieldConfig as for https://www.drupal.org/node/2312093
Merge pull request #73 from pcambra/2312093_rename_fieldinstanceconfig

Rename FieldInstanceConfig to FieldConfig