Serialization and Queue route improvement

Created by: marcus-oscarsson

Hello,

Ive made some improvements to the serialization to make it easier to extend. The jsonpickled version quickly becomes a bit tricky to manage and also adds an unnecessary layer on top of the queue. The new serialization code operates directly on the queue model so it should also be a bit faster. The exact format of the serialization can of course be discussed and I'm happy to know what you think of it. Its right now exactly the same as the one used on the client, simply to make the queue exchange easier.

I also took the opportunity to clean up and make some smaller fixes to add_datacollection, add_characterisation and update_method. I hope its a bit more readable like this, although the internals of the queue can look a bit strange some times :). The method execute_entry_with_id have also been simplified slightly.

I noticed that we store a json pickled version of the queue every time we mutate it. I exchanged the jsonpickle with cPickle to saves us some time. I noticed some delay when adding several tasks which I believe could come from the jsonpickle code.

Marcus