Add Jekyll v2 & 3 to Travis config

Author: parkr

.travis.yml

@@ -6,3 +6,16 @@ rvm:
 script: script/cibuild
 sudo: false
 cache: bundler
+notifications:
+  email: false
+
+matrix:
+  include:
+    -
+      rvm: 1.9
+      env: JEKYLL_VERSION=2.0
+  fast_finish: true
+env:
+  - ""
+  - JEKYLL_VERSION=3.0
+  - JEKYLL_VERSION=2.0