Run release builds and tests on Travis CI

Author: fitzgen

.travis.yml

@@ -41,6 +41,8 @@ before_script:
 script:
   - cargo build --verbose --features llvm_stable
   - cargo test --features llvm_stable
+  - cargo build --release --verbose --features llvm_stable
+  - cargo test --release --features llvm_stable
   - git add -A
   - git diff @
   - git diff-index --quiet HEAD