Remove cookbook's defuct ci config

.travis.yml

-language: generic
-sudo: required
-install:
-  - curl https://sh.rustup.rs -sSf > rustup; chmod +x rustup; ./rustup --default-toolchain nightly -y
-  - export PATH="$HOME/.cargo/bin:$PATH"; ./setup.sh
-script: export PATH="$HOME/.cargo/bin:$PATH"; ./ci.sh
-notifications:
-  email: false