Disable cargo cache as it doesn't appear to be helping at all

Author: palfrey

.travis.yml

@@ -5,15 +5,6 @@ env:
   global:
     - RUST_LOG=warn
 
-# Cache hints based off of https://gist.github.com/jkcclemens/000456ca646bd502cac0dbddcb8fa307
 cache:
-  cargo: true
   directories:
-    - $TRAVIS_BUILD_DIR/results # So we don't have to check all the things every time
-before_cache:
-  - rm -rfv target/debug/incremental/awesome_rust-*
-  - rm -rfv target/debug/.fingerprint/awesome_rust-*
-  - rm -rfv target/debug/deps/awesome_rust-*
-  - rm -rfv target/debug/awesome_rust.d
-  - rm -rfv target/debug/incremental/awesome_rust-*
-  - rm -rfv /home/travis/.cargo/registry/
+    - results # So we don't have to check all the things every time