lets try to fix travis github issues

lsmith77 · lsmith77 · commit e8af8e5cd6dd · 2013-01-13T15:16:30.000+01:00
diff --git a/.travis.yml b/.travis.yml
@@ -5,7 +5,7 @@ php:
   - 5.4
 
 before_script:
-  - composer install --dev
+  - composer install --prefer-source --dev
 
 script: phpunit -c tests/phpunit.xml.dist
 
