MvcUpload

Simple put the following-line inside your "Configure"-method:

public void Configure(IApplicationBuilder app) {

  app.UseMvcUpload(new MvcUploadOptions() {
    Route = "/upload",
    UploadsFolder = "Content"
  });
}

It will detect any POST-method containing files, and copy them to the selected folder

CkEditor configuration

CKEDITOR.replace('editor', {
        extraPlugins: 'uploadimage',
        imageUploadUrl: '/upload',
        uploadUrl: '/upload',
    });