Use global variables in .travis.yml file.

Author: sideshowbarker

.travis.yml

@@ -1,7 +1,8 @@
 env:
-  - CHECKER=http://validator.w3.org/nu/
-  - FILES=$(find . -name "*.html")
-  - OUTPUT=$(for file in $FILES; do curl -s -F out=gnu -F doc=@$FILE $CHECKER; done)
+  global:
+    - CHECKER=http://validator.w3.org/nu/
+    - FILES=$(find . -name "*.html")
+    - OUTPUT=$(for file in $FILES; do curl -s -F out=gnu -F doc=@$FILE $CHECKER; done)
 
 script:
   - if [ -n "$OUTPUT" ]; then printf "$OUTPUT"; echo; exit 1; fi