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/pear/net_socket/composer.json

@@ -0,0 +1,42 @@
+{
+    "authors": [
+        {
+            "email": "chuck@horde.org",
+            "name": "Chuck Hagenbuch",
+            "role": "Lead"
+        },
+        {
+            "email": "stig@php.net",
+            "name": "Stig Bakken",
+            "role": "Lead"
+        },
+        {
+            "email": "alec@php.net",
+            "name": "Aleksander Machniak",
+            "role": "Lead"
+        }
+    ],
+    "autoload": {
+        "psr-0": {
+            "Net": "./"
+        }
+    },
+    "description": "More info available on: http://pear.php.net/package/Net_Socket",
+    "include-path": [
+        "./"
+    ],
+    "license": "BSD-2-Clause",
+    "name": "pear/net_socket",
+    "support": {
+        "issues": "http://pear.php.net/bugs/search.php?cmd=display&package_name[]=Net_Socket",
+        "source": "https://github.com/pear/Net_Socket"
+    },
+    "type": "library",
+    "require": {
+        "php": ">=5.4.0",
+        "pear/pear_exception": "@stable"
+    },
+    "require-dev": {
+        "phpunit/phpunit": "^4"
+    }
+}