Add DataContext to DI

[donker]

This PR adds DataContext to DI using AddTransient so the following pattern:

            using (IDataContext ctx = DataContext.Instance())
            {
                var rep = ctx.GetRepository<SqlQuery>();
                rep.Insert(query);
            }

to

        public ApiTokenRepository(IDataContext dataContext)
        {
            this.dataContext = dataContext;
        }

....

            var rep = this.dataContext.GetRepository<ApiToken>();
            return rep.GetById(apiTokenId);