Show current commit in :PackerStatus window

[filipekiss]

First of all, thank you for packer, it's one of the best plugin managers I've ever used for (neo)vim.

I was trying to pin some plugins to some specific commits and, whenever I want to do that, I need to go into the plugin folder and manually check the hash for the current commit.

It would be nice if :PackerStatus could also show the current commit for each plugin so it would make things a lot easier.

Not sure how simple it is but I could take a look into implementing if you think it would be useful.