[Tests] restore node 0.6

Author: ljharb

.travis.yml

@@ -13,6 +13,7 @@ node_js:
   - "0.12"
   - "0.10"
   - "0.8"
+  - "0.6"
 before_install:
   - 'nvm install-latest-npm'
 install:
@@ -164,8 +165,6 @@ matrix:
       env: TEST=true ALLOW_FAILURE=true
     - node_js: "0.9"
       env: TEST=true ALLOW_FAILURE=true
-    - node_js: "0.6"
-      env: TEST=true ALLOW_FAILURE=true
     - node_js: "0.4"
       env: TEST=true ALLOW_FAILURE=true
   allow_failures: