Travis: Don't stay in chalk-engine directory

Author: tmandry

.travis.yml

@@ -3,8 +3,8 @@ rust:
   - beta
   - nightly
 script:
-  - cd chalk-engine; RUSTC_BOOTSTRAP=1 cargo build --no-default-features
-  - cd chalk-engine; RUSTC_BOOTSTRAP=1 cargo build --all-features
+  - cd chalk-engine && RUSTC_BOOTSTRAP=1 cargo build --no-default-features && cd ..
+  - cd chalk-engine && RUSTC_BOOTSTRAP=1 cargo build --all-features && cd ..
   - RUSTC_BOOTSTRAP=1 cargo test --all
   - RUSTC_BOOTSTRAP=1 cargo doc --document-private-items
 deploy: