remove cake2.5 to avoid estrict errors

.travis.yml

@@ -6,7 +6,6 @@ php:
 
 env:
   - CAKE_VERSION=master
-  - CAKE_VERSION=2.5
 
 before_script:
   - git clone --depth 1 --branch $CAKE_VERSION git://github.com/cakephp/cakephp ../cakephp && cd ../cakephp