Upgrade to sequelize v4

[davidvanleeuwen]

Please check out http://docs.sequelizejs.com/manual/tutorial/upgrade-to-v4.html

[hauru]

Thanks. Will be resolving this shortly. I'd like to get the update smoothed out so as the module could still be used with Sequelize 3.x.

[davidvanleeuwen]

@hauru True. The easiest way for people to keep on working would be doing a version bump to e.g. to 1.0.0 (as most people install packages with ^, and therefor people will have to specify this new version for v4) or the other way around were we explicitly say this in the readme that this is now for v4 and you should use 0.10.2 if you're not on v4. What do you think?

[hauru]

@davidvanleeuwen Actually the changes are not overly dramatic from our point of view and both versions of Sequelize can be easily supported along each other. I've created a separate branch for the time being. This has yet to be tested with Sequelize 4. Also there are other minor changes that i may need to take into account, like those related to data types.

[yelled3]

LGTM

[hauru]

Changes from the aforementioned branch are now in master and in NPM. @davidvanleeuwen thanks for your input! Although I didn't do a merge, your edits were helpful.

[davesag]

You might want to close this PR given you've incorporated its main features already.