Remove .travis.yml

.travis.yml

-language: rust
-env:
-  -
-  - TARGET=aarch64-unknown-linux-gnu
-  - TARGET=x86_64-unknown-redox
-rust:
-  - nightly
-install:
-  - if [ $TARGET == "aarch64-unknown-linux-gnu" ]; then sudo apt-get install gcc-aarch64-linux-gnu; fi
-before_script:
-  - rustup component add rustfmt-preview
-  - if [ -n "$TARGET" ]; then rustup target add $TARGET; fi
-script:
-  - ./ci.sh
-notifications:
-  email: false