Fixed path to travis_install.sh
Fixed path to travis_install.sh

Currently pyscaffold generates a Travis installation script named `travis_install.sh` yet `.travis.yml` refers to `install.sh`. Consequently Travis builds fail unless the developer manually modifies the path. This minor change results in a Travis setup that works out of the box.
cpaulik/pyscaffold,blue-yonder/pyscaffold,blue-yonder/pyscaffold,cpaulik/pyscaffold