Try radically changing the Travis script

.travis.yml

@@ -1,35 +1,26 @@
-matrix:
+language: python
-  include:
-    - language: rust
-      rust:
-      - stable
-      - beta
-      - nightly
-      matrix:
-        allow_failures:
-          - rust: nightly
-      cache: cargo
 
-    # http://kiki.to/blog/2016/02/04/talk-continuous-integration-with-lua/
+env:
-    - language: python
+  - RUST="stable" LUA="lua=5.1"
-      env:
+  - RUST="beta" LUA="lua=5.1"
-        - LUA="lua=5.1"
 
-      before_install:
+before_install:
   - pip install hererocks
   - hererocks lua_install -r^ --$LUA
   - export PATH=$PATH:$PWD/lua_install/bin
+  - curl https://sh.rustup.rs -sSf | sh -s -- -y --default-toolchain $RUST
 
-      install:
+install:
   - luarocks install luafilesystem
   - luarocks install busted
   - luarocks install luacov
   - luarocks install luacov-coveralls
   - luarocks install luacheck
 
-      script:
+script:
   - cd plugin && luacheck . && cd ..
   - lua -lluacov spec.lua
+  - cargo test --verbose
 
-      after_success:
+after_success:
   - luacov-coveralls -e $TRAVIS_BUILD_DIR/lua_install