Bump to php 5.5

Author: Nyholm

.travis.yml

@@ -7,7 +7,6 @@ cache:
         - $HOME/.composer/cache
 
 php:
-    - 5.4
     - 5.5
     - 5.6
     - 7.0
@@ -26,7 +25,7 @@ matrix:
         - php: hhvm
     fast_finish: true
     include:
-        - php: 5.4
+        - php: 5.5
           env: COMPOSER_FLAGS="--prefer-stable --prefer-lowest" COVERAGE=true TEST_COMMAND="composer test-ci"
 
 before_install:

composer.json

@@ -9,7 +9,7 @@
         }
     ],
     "require": {
-        "php": ">=5.4",
+        "php": "^5.5|^7.0",
         "symfony/options-resolver": "^2.6|^3.0",
         "php-http/httplug": "^1.0",
         "php-http/message-factory": "^1.0.2",