Set up CI, add format and test scripts.

Remove unused Cargo dependencies.

.travis.yml

@@ -0,0 +1,43 @@
+# Travis CI script borrows heavily from CraneStation/wasmtime project.
+os:
+    - linux
+    - osx
+language: rust
+rust:
+    - stable
+    - beta
+    - nightly
+matrix:
+    allow_failures:
+        # We try to be compatible with beta and nightly, but they occasionally
+        # fail, so we don't allow them to hold up people using stable.
+        - rust: beta
+        - rust: nightly
+    # Similarly, we don't need to hold up people using stable while we wait
+    # for the results which may fail.
+    fast_finish: true
+dist: xenial
+sudo: false
+branches:
+    only:
+        - master
+before_script:
+    # If an old version of rustfmt from cargo is already installed, uninstall
+    # it, since it can prevent the installation of the new version from rustup.
+    - cargo uninstall rustfmt || true
+    - cargo install --list
+    # If we're testing beta or nightly, we still need to install the stable
+    # toolchain so that we can run the stable version of rustfmt.
+    - rustup toolchain install stable
+    # Install the stable version of rustfmt.
+    - rustup component add --toolchain=stable rustfmt-preview
+    - rustup component list --toolchain=stable
+    - rustup show
+    - rustfmt +stable --version || echo fail
+    # Sometimes the component isn't actually ready after being installed, and
+    # rustup update makes it ready.
+    - rustup update
+    - rustfmt +stable --version
+script: ./test-all.sh
+cache:
+    cargo: true