Fixed build (#3)

* * remove php 5.5.9 support
* fixed CI test build for php 7.1
* added composer.lock file

Author: liderman

.travis.yml

@@ -3,9 +3,6 @@ language: php
 sudo: false
 
 php:
-  - 5.5.9
-  - 5.6
-  - 7.0
   - 7.1
   - 7.2
   - nightly
@@ -17,4 +14,4 @@ cache:
 before_script:
   - composer install
 
-script: composer test
+script: composer test

README.md

@@ -55,5 +55,5 @@ Features
 Requirements
 -----------
 
-* PHP >= 5.5.9.
+* PHP >= 7.1
 

composer.json

@@ -27,11 +27,11 @@
     },
     "minimum-stability": "dev",
     "require": {
-        "php": ">=5.5.9"
+        "php": "^7.1"
     },
     "require-dev": {
         "phpunit/phpunit": "^5.0.0",
-        "phpstan/phpstan": "^0.9.0"
+        "phpstan/phpstan": "^0.10.0@dev"
     },
     "scripts": {
         "phpunit": [
@@ -45,4 +45,4 @@
             "@phpstan"
         ]
     }
-}
+}