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/sebastian/global-state/composer.json

@@ -11,10 +11,10 @@
         }
     ],
     "require": {
-        "php": ">=5.3.3"
+        "php": "^7.0"
     },
     "require-dev": {
-        "phpunit/phpunit": "~4.2"
+        "phpunit/phpunit": "^6.0"
     },
     "suggest": {
         "ext-uopz": "*"
@@ -27,11 +27,14 @@
     "autoload-dev": {
         "classmap": [
             "tests/_fixture/"
+        ],
+        "files": [
+            "tests/_fixture/SnapshotFunctions.php"
         ]
     },
     "extra": {
         "branch-alias": {
-            "dev-master": "1.0-dev"
+            "dev-master": "2.0-dev"
         }
     }
 }