Revert "removed 3.0 constraints from 2.7 composer files"

This reverts commit 5503804cf91f4ede81b94b34609653c013139038.

Author: fabpot

composer.json

@@ -19,12 +19,12 @@
         "php": ">=5.3.9"
     },
     "require-dev": {
-        "symfony/phpunit-bridge": "~2.7",
-        "symfony/event-dispatcher": "~2.1",
-        "symfony/expression-language": "~2.6",
-        "symfony/http-foundation": "~2.4",
-        "symfony/translation": "~2.0,>=2.0.5",
-        "symfony/validator": "~2.5,>=2.5.5",
+        "symfony/phpunit-bridge": "~2.7|~3.0.0",
+        "symfony/event-dispatcher": "~2.1|~3.0.0",
+        "symfony/expression-language": "~2.6|~3.0.0",
+        "symfony/http-foundation": "~2.4|~3.0.0",
+        "symfony/translation": "~2.0,>=2.0.5|~3.0.0",
+        "symfony/validator": "~2.5,>=2.5.5|~3.0.0",
         "psr/log": "~1.0",
         "ircmaxell/password-compat": "1.0.*"
     },