Support for optimistic locking

[fishcharlie]

dynamoose/dynamoose#16

[dolsem]

I was terribly busy in the last few months, so couldn't contribute to this library. I will definitely get this done in the next several weeks.

[dolsem]

The plugin is fully functional, located at https://github.com/dolsem/dynamoose-plugin-optimistic-locking. However, it relies on my fork of Dynamoose while #645 is not merged.

[rodrigogs]

@dolsem I'm sorry but... how to use it with v2?

MyModel.plugin is not a function

[dolsem]

@rodrigogs I don't think v2 has plugin support. Hopefully v3 will.

[rodrigogs]

Oh, I see. Well... it's very disappointing since v1 had it.

I'm stuck in v1(which has some ugly bugs) and v2 looks like a downgrade :/

[dolsem]

@rodrigogs what bugs are you concerned about specifically? I find v1 to be pretty stable overall. Admittedly, some bugs are present, but I havent seen anything critical for my use case personally.

[rodrigogs]

You cant use Model.update for instance, because it doesn't work, I have to retrieve the doc and execute doc.save().

I know, It has an easy workaround, that's why I called it an ugly bug :P