drop official support for node 0.6

.travis.yml

@@ -1,6 +1,5 @@
 language: node_js
 node_js:
-  - 0.6
   - 0.8
   - '0.10'
   - 0.11
@@ -9,4 +8,4 @@ before_install:
   - "test $TRAVIS_NODE_VERSION = '0.6' && npm install -g npm@1.3.26 || npm install -g npm"
 matrix:
   allow_failures:
-    - node_js: 0.11
+    - node_js: 0.11