public async Task<IHttpActionResult> PutContributor(int id, Contributor contributor)
        {
            if (!ModelState.IsValid)
            {
                return BadRequest(ModelState);
            }

            if (id != contributor.Id)
            {
                return BadRequest();
            }

			contributor.Projects.ForEach(p => db.Projects.Attach(p));

	        db.UpdateGraph(contributor, map => map.AssociatedCollection(c => c.Projects));
			
            try
            {
                await db.SaveChangesAsync();
            }
            catch (DbUpdateConcurrencyException)
            {
                if (!ContributorExists(id))
                {
                    return NotFound();
                }
                else
                {
                    throw;
                }
            }

            return StatusCode(HttpStatusCode.NoContent);
        }
        public async Task<IHttpActionResult> PostContributor(Contributor contributor)
        {
            if (!ModelState.IsValid)
            {
                return BadRequest(ModelState);
            }

            db.Contributors.Add(contributor);
            await db.SaveChangesAsync();

            return CreatedAtRoute("DefaultApi", new { id = contributor.Id }, contributor);
        }