Install mcrypt extension via PECL with TravisCI

Author: jstruzik

.travis.yml

@@ -14,6 +14,7 @@ matrix:
 
 before_install:
    - export ALLOW_FAILURE=1; if [ "$TRAVIS_PHP_VERSION" != "hhvm" ] && [ "$TRAVIS_PHP_VERSION" != "nightly" ]; then export ALLOW_FAILURE=0; fi
+   - pecl install mcrypt-1.0.2
 
 install:
   - composer self-update