.travis.yml: Force Travis CI to install the version that we built. Fixes jakirkham/nanshe#228.
.travis.yml: Force Travis CI to install the version that we built. Fixes jakirkham/nanshe#228.

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