Add support for filter=complete in the branch call


#1

We’re looking for a way to find the latest successful build on a specific branch. It seems that Circle’s API end point that returns a list of builds on a specific branch
https://circleci.com/api/v1.1/project/:vcs-type/:username/:project/tree/:branch
does not support the param filter=completed. The support for this param will facilitate many companies.


#2