Fix .travis.yml to use scripts/bootstrap (old was scripts/install)
Fix .travis.yml to use scripts/bootstrap (old was scripts/install)

`.travis.yml` references `scripts/install`. This commit changes it
to `scripts/boostrap`, the new location for the installer.

hypatia-software-org/hypatia-engine,hypatia-software-org/hypatia-engine,lillian-lemmer/hypatia,lillian-lemmer/hypatia