Fix spelling mistake: exclutions -> exclusions

Author: shane-smith

.travis.yml

@@ -25,7 +25,7 @@ env:
   - DB=mysql
   - DB=pgsql
 
-# optionally set up exclutions and allowed failures in the matrix
+# optionally set up exclusions and allowed failures in the matrix
 matrix:
   exclude:
     - php: hhvm