Update travis to be more like laravel 5.4

Author: jimmypuckett

.travis.yml

@@ -5,7 +5,7 @@ php:
   - 5.5
   - 5.6
   - 7.0
-  - hhvm
+  - 7.1
 
 env:
   global:
@@ -20,6 +20,14 @@ matrix:
 
 sudo: false
 
+cache:
+  directories:
+    - $HOME/.composer/cache
+
+before_install:
+  - if [[ $TRAVIS_PHP_VERSION != 7.1 ]] ; then phpenv config-rm xdebug.ini; fi
+  - travis_retry composer self-update
+
 install:
   - if [[ $setup = 'basic' ]]; then travis_retry composer install --no-interaction --prefer-source; fi
   - if [[ $setup = 'stable' ]]; then travis_retry composer update --prefer-source --no-interaction --prefer-stable; fi
@@ -29,4 +37,4 @@ before_script: mkdir -p build/logs
 
 script: vendor/bin/phpunit
 
-after_script: if [[ $TRAVIS_PHP_VERSION != 'hhvm' ]]; then vendor/bin/coveralls -v -n; fi
+after_script: vendor/bin/coveralls -v -n