Fetch users by GitHub ID instead of username
Fetch users by GitHub ID instead of username

This will also update the username if the user was renamed on GitHub.

kidaa/travis-core,developerfm/travis-core,Tiger66639/travis-core,travis-ci/travis-core,kidaa/travis-core,kidaa/travis-core,jantman/travis-core,final-ci/travis-core,final-ci/travis-core,Tiger66639/travis-core,developerfm/travis-core,travis-ci/travis-core,developerfm/travis-core,jantman/travis-core,GistIcon/travis-core,final-ci/travis-core,Tiger66639/travis-core,GistIcon/travis-core,GistIcon/travis-core,travis-ci/travis-core