Field values are stored in dictionary entries as json string.
Field objects are stored as JSON array inside dictionary entity.
Fixed conversion of fields between DTOs and dictionary entries.
- fixed bug in JSON serialization
- refactored domain model for dictionary fields, removed unused fields
- fixed adding of concepts to ES index
- languages are stored as JSON string in dictionary table
- sections are stored as JSON string in dictionary table
- added compatibility fixes for SQL Server
- refactored services managing dictionary details
- disabled DEBUG log messages for ElasticSearch classes
- merged changes from 'json-columns' branch
Merge remote-tracking branch 'origin/master'

Conflicts:
	package.json
- merged changes from 'json-columns' branch