travis: Add clippy/rustfmt job

Signed-off-by: Matthias Beyer <mail@beyermatthias.de>

.travis.yml

@@ -55,6 +55,18 @@ matrix:
           script:
             - cargo build --all --all-features -j 1  || exit 1
             - cargo test  --all --all-features -j 1  || exit 1
+        - language: rust
+          rust: stable
+          name: clippy
+          cache:
+            directories:
+              - /home/travis/.cargo
+          before_cache:
+            - rm -rf /home/travis/.cargo/registry
+          install:
+            - rustup component add clippy
+          script:
+            - cargo clippy --all --all-targets
 
 
 addons: