Add pear modules, mail and net_smtp via composer (#93)

Add pear modules, mail and net_smtp via composer, remove php 5.6 build due to phpunit 6

lib/composer/vendor/symfony/debug/composer.json

@@ -16,15 +16,14 @@
         }
     ],
     "require": {
-        "php": ">=5.5.9",
+        "php": "^5.5.9|>=7.0.8",
         "psr/log": "~1.0"
     },
     "conflict": {
         "symfony/http-kernel": ">=2.3,<2.3.24|~2.4.0|>=2.5,<2.5.9|>=2.6,<2.6.2"
     },
     "require-dev": {
-        "symfony/class-loader": "~2.8|~3.0",
-        "symfony/http-kernel": "~2.8|~3.0"
+        "symfony/http-kernel": "~2.8|~3.0|~4.0"
     },
     "autoload": {
         "psr-4": { "Symfony\\Component\\Debug\\": "" },
@@ -35,7 +34,7 @@
     "minimum-stability": "dev",
     "extra": {
         "branch-alias": {
-            "dev-master": "3.1-dev"
+            "dev-master": "3.4-dev"
         }
     }
 }