Show commits by author

It's useful to see a list of commits by author for a project, and also by branch. GitHub supports this by project (not branch). We should add this because it is very useful for quickly looking up what someone has been working on.

Example: https://github.com/gitlabhq/gitlabhq/commits?author=rymai

Proposal

Add the ability to filter the commit list by author

Links

https://github.com/gitlabhq/gitlabhq/commits?author=rymai

Customers

https://gitlab.my.salesforce.com/0016100000YTQ6w