Introduced IArticleService.
Introduced ArticleService.
Implemented GetAsync method.
Implemented AddOrModifyAsync.
Implemented Remove method.
Implemented Delete method.
Addressed using ArticleService in controller instead of repository.
Implemented PostAsync.
Addressed acceptance-test PostAsync.
Addressed CA1024.
Addressed acceptance-test PostAsync - Modify case.
Renamed some acceptane tests.
Renamed formatter classes.
Removed unncessary code line.
Renamed entity property.
Renamed ArticleWord properties.
Implemented adding article words when adding article.
Addressed Adding article words asynchronooulsy, which doesn't block

client requests.
Addressed not throwing when adding duplicated article.
Introduced ArticleWordRepository.