Updated travis.ci configuration file

Author: norberttech

.travis.yml

@@ -1,13 +1,31 @@
 language: php
 
-php:
-    - 5.3
-    - 5.4
-    - 5.5
+sudo: false
 
-before_script:
-    - curl -s http://getcomposer.org/installer | php
-    - php composer.phar --dev install
+cache:
+  directories:
+    - $HOME/.composer/cache
+    
+matrix:
+  include:
+    - php: 5.3
+      env: DEPENDENCIES='low'
+    - php: 5.3
+    - php: 5.4
+    - php: 5.5
+    - php: 5.6
+    - php: 7.0
+    - php: hhvm
+  allow_failures:
+    - env: DEPENDENCIES='low'
+
+before_install:
+  - composer self-update
+
+install:
+  - export COMPOSER_ROOT_VERSION=dev-master
+  - if [ "$DEPENDENCIES" != "low" ]; then composer update; fi;
+  - if [ "$DEPENDENCIES" == "low" ]; then composer update --prefer-lowest; fi;
 
 script:
-  - bin/phpspec run -v -f pretty
+  - ./bin/phpspec run --format=pretty