Disable travis build cache

Periodically the travis build cache gets poisoned and needs to be cleared manually. Due to the low volume of activity here these days, let's disable it altogether.

Author: mszabo-wikia

.travis.yml

@@ -29,10 +29,5 @@ script:
   - git diff $TRAVIS_BRANCH..HEAD --name-only --diff-filter ACMRT | grep \.php$ | grep -Ev '(lib/composer|lib/Swagger|/templates/)' | xargs -n 1 php -l
   - cd tests && ./php-tests.sh
 
-# cache compiled version of pecl extensions
-cache:
-  directories:
-    - /home/travis/.phpenv
-
 notifications:
   email: false