Update Travis configuration

.travis.yml

@@ -3,8 +3,10 @@ language: php
 php:
   - 5.6
   - 7.0
+  - 7.0snapshot
   - 7.1
-  - nightly
+  - 7.1snapshot
+  - master
 
 env:
   matrix:
@@ -16,14 +18,16 @@ sudo: false
 before_install:
   - composer self-update
   - composer clear-cache
+  - if [ $(phpenv version-name) = "5.6" ]; then wget https://phar.phpunit.de/phpunit-5.7.phar -O phpunit.phar; fi
+  - if [ $(phpenv version-name) != "5.6" ]; then wget https://phar.phpunit.de/phpunit.phar; fi
 
 install:
   - if [[ "$DEPENDENCIES" = 'high' ]]; then travis_retry composer update --no-interaction --no-ansi --no-progress --no-suggest --optimize-autoloader --prefer-stable; fi
   - if [[ "$DEPENDENCIES" = 'low' ]]; then travis_retry composer update --no-interaction --no-ansi --no-progress --no-suggest --optimize-autoloader --prefer-stable --prefer-lowest; fi
 
 script:
-  - wget https://phar.phpunit.de/phpunit-5.7.phar
-  - php phpunit-5.7.phar
+  - php phpunit.phar
 
 notifications:
   email: false
+