.travis.yml: Pin `conda-build`.
.travis.yml: Pin `conda-build`.

jakirkham/rank_filter,nanshe-org/rank_filter,nanshe-org/rank_filter,DudLab/rank_filter,DudLab/rank_filter,jakirkham/rank_filter,nanshe-org/rank_filter,jakirkham/rank_filter,DudLab/rank_filter