Metadata when sending data?

[jayztemplier]

Hi!

First of all, thank you for this super useful library :)
I was wondering how can I set some metadata when I send an object to the aws3 bucket?
I would like to set a metadata like @"title" : @"title_of_my_image".

Thank you in advance for your help!
Jeremy.

[jayztemplier]

I created a pull refresh that allows us to handle metadata easily:
#4