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/filp/whoops/composer.json

@@ -2,7 +2,7 @@
     "name": "filp/whoops",
     "license": "MIT",
     "description": "php error handling for cool kids",
-    "keywords": ["library", "error", "handling", "exception", "whoops", "zf2"],
+    "keywords": ["library", "error", "handling", "exception", "whoops", "throwable"],
     "homepage": "https://filp.github.io/whoops/",
     "authors": [
         {
@@ -16,7 +16,7 @@
         "psr/log": "^1.0.1"        
     },
     "require-dev": {
-        "phpunit/phpunit": "^4.8 || ^5.0",
+        "phpunit/phpunit": "^4.8.35 || ^5.7",
         "mockery/mockery": "0.9.*",
         "symfony/var-dumper": "^2.6 || ^3.0"
     },