build: reduce install on Node.js 0.6

Author: dougwilson

.travis.yml

@@ -7,8 +7,11 @@ node_js:
 - "1.0"
 - "1.8"
 sudo: false
+before_install:
+  # Setup Node.js version-specific dependencies
+  - test $TRAVIS_NODE_VERSION != '0.6' || npm rm --save-dev istanbul
 script:
   - "test $TRAVIS_NODE_VERSION != '0.6' || npm test"
   - "test $TRAVIS_NODE_VERSION  = '0.6' || npm run-script test-travis"
 after_script:
-  - "test $TRAVIS_NODE_VERSION != '0.6' && npm install coveralls@2 && cat ./coverage/lcov.info | coveralls"
+  - "test $TRAVIS_NODE_VERSION != '0.6' && npm install coveralls@2 && cat ./coverage/lcov.info | coveralls"