KH-204: Added DTO for code element changes
KH-204: add getKoodiVersio to KoodiBusinessService

Method was already implemented actually, just changed its visibility to
public.
KH-204: initial interfaces and implementations
KH-204: Refactored test and added couple future test cases
KH-204:  Wrote testcase with added support functionality

Added some
KH-204: Add changed metadatas to DTO

SimpleKoodiMetadataDto contains only changed and new KoodiMetadatas but
not removed (for now, since there is no use case).
KH-204: Added removedMetadatas to Dto

Also with test case for new metadata.
KH-204:  Added update date to dto
KH-204: Add changed valid thru dates to dto
KH-204: Add changed Tila to dto
KH-204: Rest interface for getting changes

to code element.
KH-204: Use 200 not 202
KH-204: Show only non empty fields
KH-204: checks whether metadata exists for language

Before adding it to removed metadatas.
KH-204: Interface change

Paremeter for whether we should compare to latest accepted version or
not
KH-204: Interface for fetching koodi

From koodibusinessService. Ensure collections are initialized.
KH-204: Compares against latest accepted version

If compareToLatestAccepted is true.
KH-204: REST-method for getting code changes accepts

now boolean queryparam whether changes should be compared against latest
accepted version or latest version. Had to initialize metadatas in
koodibusiness service.
KH-204: DateComparator

Helps verifying against which version of codes or code element we need
to compare against.
KH-204: Check for same time in DateComparator