fix: symfony/event-dispatcher ~3.0 requires php >=5.5.9

BREAKING CHANGE: drop PHP 5.4 support.

Closes #2

Author: whizark

.travis.yml

@@ -3,7 +3,6 @@ sudo: false
 language: php
 
 php:
-  - '5.4'
   - '5.5'
   - '5.6'
   - '7.0'

composer.json

@@ -33,7 +33,7 @@
         "source": "https://github.com/devaloka/devaloka"
     },
     "require"          : {
-        "php"                     : ">=5.4.0",
+        "php"                     : ">=5.5.9",
         "composer/installers"     : "~1.0",
         "pimple/pimple"           : "~3.0",
         "symfony/event-dispatcher": "~3.0"