Add support for a drop-in replacement for sync.Mutex and sync.RWMutex

[michaelfinch]

Per the discussion in #2, it would be nice to have client(s) that implement the same methods as sync.Mutex and sync.RWMutex

[smartinov]

Think I'll have a look at it over the weekend, possibly make a pull request!

Any special guidelines i should adhere?

[michaelfinch]

Hey @smartinov. So after thinking about this more, I don't think it makes sense to include this functionality in this package right now. Currently the package does one very specific thing - it provides a mongo client capable of creating basic lock primitives - and I would like to try and keep it that way. Imo the best way to do what you want is, as you've already done, implement your own small wrapper around a lock.Client within your code. I'm not opposed to potentially changing the client methods, but I don't want to create additional clients here.

[smartinov]

Hi! Sure, no problem! Makes sense!

Maybe it would be good to extend it with something like NewClient but to optionally allow ensuring indexes automatically, by using something like sync.Once or something?

How's that sound?

[michaelfinch]

I like that. Let's add a CreateIndexes method to the client that creates all of the indexes described in the README. Feel free to add it, or else I will next week.

[smartinov]

#4 Implements the CreateIndexes Method